Luna Luna , known as Ruka in the Japanese version , sometimes romanized as Luca , Luka , or Ruca , ( see below ) , is Leo ' s fraternal twin sister and a Signer who possessed the front claw Mark of the Dragon . She and Leo aid Yusei Fudo , whom they admire and support , in his Duels . Luna is the younger , frail , calmer , more collected of the twins . Luna tends to get tired right after a Duel . She has the ability to communicate with Duel Monsters after having spent ample time with Duel Spirits in a different dimension during a coma . She and her brother also have vignette series before each episode in the " Dark Signers " arc known as card of the week . Design . Appearance . Luna ' s usual outfit is similar to her brother Leo ' s , consisting of a light pink short - sleeved jacket over a long - sleeved red shirt with golden markings . She also wears light purple shorts with a red belt and sneakers with black and pink markings and high socks . She has gray - gold eyes just like her brother . On formal occasions , Luna wears a pink dress , a white cardigan and a pink ribbon below her neck . When she ' s sleeping , she wears pink pajamas with a nightcap . When at school , she wears the Duel Academy academy girls uniform with a red bookbag . Luna ' s green hair is done up in two high ponytails on either side of her head with two shoulder - length bangs on both sides of her face . Her Duel Disk has a pink and white trim . It was modified by Yusei to fit her left arm . After the timeskip she grows her hair out and forgoes the ponytail and wears a pink blouse and sandals with white shorts . Personality . Luna is a very polite , kind and sweet young girl . She does occasionally criticize her brother ( more often in the dub ) , but deeply cares for him . She also has shown to be quite intelligent and calculating in her Duels Etymology . Linework by Kazuki Takahashi used the spellings Rua and Ruka for the Japanese names of Leo and Luna . Throughout the Japanese anime , the spellings have alternated between Lua and Luca and Rua and Ruka . The official subtitles for " Yu - Gi - Oh ! 5D ' s " confirmed the English translation to be Luca , however Takahashi ' s reference confirms it to instead be Ruka . The differing names is due to Japanese speakers pronouncing " L " and " R " as the same sound . The 4Kids Entertainment website listed Luca ' s English name as Luna in the characters page , while Lua had his changed to Luka . Luka later had his name changed to Leo , while Luna ' s stayed as Luna . Abilities . Luna has the unique ability to sense and communicate with Duel Monster Spirits . Her most notable spirit partners are Kuribon , Regulus and Ancient Fairy Dragon . In addition to her connection with Duel spirits , she has also been able to travel to the Duel Monsters Spirit World at the risk of having her body comatose in the real world ( with the exception of when Regulus cast a spell to transfer her to the Spirit World . ) . She also has an ability to sense someone at times when they ' re in danger , such as when her brother was against Devack and in pain , or when Yusei was being shocked by officers near her house . In addition to this , she can feel or sense a person ' s Deck , such as before Yusei woke up , and Akiza ' s first Duel in the Fortune Cup where she could feel Akiza ' s Deck suffering . Health . Luna is a very frail girl , getting very easily tired and does not get out much because of it . When she was younger , she fell into a coma for several days . However , she starts to get out more as the series progressed , and becomes less frail and tired after the " Dark Signers " arc , even going to Duel Academy with Leo , but is still badly hurt when taking on any real damage . She also suffered a heart attack after receiving several electric shocks and watching Leo die . Biography . History . Luna lives together with her twin brother Leo in the Tops residential area . They spend most of their time alone together as their parents are usually at work . They were initially educated via the internet , so they spend most of their time inside . Luna has been Dueling since the age of three . Once , she lapsed into a coma after a Duel , and did not awaken for a month . During that month , her mind lived in the Duel Monsters Spirit World under the protection of Ancient Fairy Dragon , one of the Signer Dragons . Before waking up , she promised she would always be there to defend the Duel Spirits from evil that threatened the land . However , the pressure from undertaking such a task alone was too much and Luna had to forsake her promise , allowing the Duel Monsters Spirit World to fall later into the influence of Zeman the Ape King , who without much difficulty with the help of his army , turned most of the spirits into stone , and eventually imprisoned them . He was even able to capture and rock - seal Ancient Fairy Dragon ' s spirit into the mountains . Luna later returns and saves the spirits with some help from Leo . Fortune Cup . Luna was selected to participate in the Fortune Cup . She was told she was randomly selected , but was invited so Iliaster could confirm that she is a Signer . However , not up to participating , Leo planned to disguise himself as her and Duel in her place . Due to their Marks , Luna was able to sense Yusei when he was attacked by Sector Security . She and Leo rescued him after his Duel with Trudge and the resultant Duel Runner crash near their home . Yusei wanted to leave , feeling that he was putting them in danger , but Leo talked him into a Duel . After Yusei won , Luna and Leo manage to get him to stay for the night . They awake the next morning to find that Yusei had left after modifying their Duel Disk s to fit their small arms . The next day , Leo entered the Fortune Cup disguised as Luna , but using Zigzix ' s Signer - detecting technology , Lazar was not only able to determine that Greiger Dueled Leo instead of Luna , but also that Luna is a Signer . Luna faced off against Professor Frank due to Rex Goodwin ' s consolation game , but in the middle of the Duel , both she and Leo are hypnotized . Luna ' s conscious self awakens in the Duel Monster Spirit World , where she sees the degradation of the dimension and decides to uphold her promise from then on . Before she concludes the match , Luna is called a Signer by Frank , although unaware at that moment of its meaning or its relationship with her Claw Mark of the Dragon . Only Yusei becomes aware of her being one , though he does not tell the others . Eventually , though , they learn this after his Duel against Akiza Izinski . She witnesses the appearance of the Crimson Dragon during Yusei and Jack Atlas ' title Duel . Because of the Duel , Luna , along with the three other Signers , are transported to an alternate dimension . There they are shown two visions ; one of the Stairway to the Dragon Star , where the People of the Stars were worshiping the ancient Signers , and the other showing Satellite being destroyed , and in its place the appearance of a spider geoglyph . After that , Luna and Akiza are the only ones to witness Jack ' s defeat . As they all return to the stadium , she reunites with Yusei in order to leave through an underground tunnel . Luna talks to Yusei about the vision , who responds that he doesn ' t know what it means , but that in any case he must prevent it from happening . She also asks him what is a Signer , to which Yanagi intervenes in order to answer to her . Luna learns its meaning and its relationship with her along birthmark , along with the fact that that Yusei , Jack , and Akiza are Signers too . Dark Signers . After the Dark Signers started taking action , Luna has been having vivid dreams of the Signer Dragons and the Crimson Dragon battling an unknown evil . Ancient Fairy Dragon gets pulled into an abyss , showing that the Dragon ' s card is currently with the Dark Signers . As Yusei is about to come face to face with Kalin Kessler , his Mark of the Dragon reacts along with Luna ' s , Jack ' s , and Akiza ' s . She notices this and Leo does too as he is nearby . Luna is able to sense that Yusei is the reason of why her Mark of the Dragon glows . After Yusei takes a hit by " Earthbound Immortal Ccpac Apu " , Luna ' s Mark of the Dragon gets etched into her arm . Leo explains to Tanner and Yanagi that Luna is frail and therefore she can ' t go out much . Luna accompanies Leo , Tanner , and Yanagi to the Arcadia Movement , where they meet Sayer . He induces them to sleep with gas , wanting to make Luna a member of the organization due to her powers . Luna wakes up next to Akiza , where they both watch the Duel between Sayer and Leo . Akiza tells Luna that Sayer wants to test her brother to find out if he possesses any similar powers . Leo passes out upon losing as Luna calls out to him . After the Duel , Akiza informs her that Leo isn ' t in danger . Luna clarifies Leo doesn ' t possess any powers , but he was still kept in a place with Luna . Akiza tells her that in any case the Arcadia Movement will be her new home , as she doesn ' t want Luna to walk through the same path she did ; the path of being feared and abandoned by others because of her powers . Luna asks Ancient Fairy Dragon for help , but her spirit says that she cannot rescue her and that she is witnessing the posing threat of the Dark Signers . In order to set her free , Luna must join forces with her servant , Regulus , who will eventually appear to her . Once Ancient Fairy Dragon is set free , she promises to protect Luna from the enemy . After Tanner frees her and Leo , while fleeing the building , she senses Akiza in a Duel as her Mark of the Dragon begins to glow . As she decides to find her , the four of them run into Misty and Akiza ' s Duel . As Luna notices the lizard Dark mark , she recalls the vision of the battle between the Crimson Dragon and the " Earthbound Immortals " again . Right as Misty is about to Summon her " Earthbound Immortal " , Luna ' s dragon birthmark protects her , Leo , Tanner , and Yanagi from being sacrificed for its Summon . Tanner gets her and Leo out in time as the building collapses . After Akiza lands in the hospital in a comatose state , Luna is there along with her brother and Jack . As with the rest of the people there , she witnesses the Duel between Yusei and Akiza . After it concludes , Akiza decides to help them in their fight against the Dark Signers . After it , Luna along with Leo and the other Signers are invited by Rex Goodwin into his house , as he wants to reveal to them some secret concerning the Crimson Dragon . She learns from him that those who are Signers exist within some sort of " fate " , derived from the Crimson Dragon ' s power , one which cannot be escaped from . That strange fate was the one responsible for that all of the four Signers to have actually met in someway . Thus , the " Fate of the Signers " unites each and every one of Yusei , Jack , Akiza and her own destiny together in order to guide them all . Nonetheless , according to Goodwin the four of them are not only Duelist s chosen by the Crimson Dragon itself , but they are also the reincarnations of the ancient Signers themselves . Also already predicted thousands of years ago the four of them would encounter one another . She also learns about the Dark Signers ' abilities involving their powers and use of the " Earthbound Immortals " . According to Goodwin , their powers that manifest in a Duel come from the underworld . Also as they appeared on the city , many casualties occurred just like in Satellite due to their Immortals . Luna along with the others realize the shocking truth behind the transformation of an individual into a Dark Signer : It can ' t be reverted due to the fact those individuals are dead and that they are resurrected because of a powerful phenomenon occurring on the other side of the Underworld . After this she cheers Leo up , who feels he can ' t be a hero or protect her because of having lost to Sayer , by saying he doesn ' t have to be a hero , and to just protect her like he always has . Like Jack and Akiza , she ' s present along with her brother during and after Yusei ' s match against Roman Goodwin . After it concludes , the rest of the Dark Signers show themselves , as their ancient battle is about to commence . Later on as each one of the Signers is set on defeating their respective opponent , they split up to each of the four control units of the Original Ener - D Reactor . As Luna and Leo are taken by Trudge to where Devack is waiting , she instead travels into the Duel Monsters Spirit World in order to free Ancient Fairy Dragon . Due to this , Leo bravely challenges Devack to a Duel in her place , as he is determined to fulfill his promise of protecting her . In the Spirit World , Luna searches for Regulus . She gets chased down by an army of monkey spirits commanded by Zeman the Ape King , who is Devack ' s Dark Synchro Monster . The monkey army captures " Kuribon " , " Sunny Pixie " , and " Sunlight Unicorn " . She evades them with the help of a spirit named Torunka . Luna eventually finds Regulus at Pojar Forest and tells to the Lion the promise long ago made to Ancient Fairy Dragon . However , because of the Cursed Needle in its ankle , he understands her in the opposite way . After a chase , Luna is finally able to dispose of the Needle and convince the White Lion of her righteous intentions by showing her Mark of the Dragon . After that Regulus , Luna , and Torunka set off to Zeman ' s castle . They are able to get inside by tricking Zeman into thinking that Luna is a servant of Zeman and has caught Regulus . She also tells Zeman to curse both Regulus and Ancient Fairy Dragon in order to minus Ancient Fairy Dragon completely . Zeman falls for this and is about to release her . However , Zeman finds out they were trying to trick him and orders his army to attack them . He is eventually killed by Regulus , and at the same moment , Leo defeats him in the real world . Devack then Summons his " Earthbound Immortal Cusiullu " and attacks Leo , who withstands the assault . Torunka sends Luna back to the real world , where she takes the the Duel for her injured brother . Devack then attempts to use " Ancient Fairy Dragon " against Luna , but she forces him to sacrifice it in order to save his " Earthbound Immortal " from being destroy ed , which allows her to Summon her dragon to her side of the field . Once this is done , Regulus appears and breaks the dragons ' chains , freeing it at last . Luna then proceeds to use both " Ancient Fairy Dragon " , equip ped with " Pain to Power " and " Power Tool Dragon " , equipped with " Rocket Pilder " , to destroy " Cusillu " and defeat Devack . After the Duel , Luna picks up the " Ancient Fairy Dragon " card and also finds a " Regulus " cards . Following Crow ' s Shadow Turbo Duel against Greiger , Luna along with her brother , Trudge , and Crow himself witness the rematch between Yusei and Kalin Kessler . After the extreme Duel ends , Luna , Leo , and Trudge accompany Yusei as he decides to go to the Original Ener - D Reactor directly in order to Duel against Roman one more time . She watches the Duel between Yusei and Roman as it ends up with Yusei´s victory . After the Duel , she watches in horror as Roman blows up the bridge and drops Yusei into the Ener - D Reactor . Like the rest she´s glad , when Yusei returns , though unconscious . After he finally wakes up and that everyone eventually goes up through the same stairs they used before , they all notice purple sparks in the distance . She then knows that not only has Jack won , but also activated the third Tower . Knowing that the last Tower to be activated is Akiza´s task , Luna along with Leo , Trudge , and Yusei all go to where it is . Arriving at an old and abandoned carnival , they split and began looking for her and Mina , except for the twins who look for them together . After Sayer awakens Akiza ' s power and is transformed once again into the Black Rose , they notice the tornado that has materialized on the carnival caused by the Synchro Summoning of " Black Rose Dragon " . As they get to the area where the Duel is taking place , they both notice Akiza´s powers having once again manifested even stronger . After Mina and Trudge arrive , they all watch the outcome of the match , with Akiza emerging victorious . However , they notice that its too late for the last Tower to be activated , as the sun has already set . The Condor geoglyph appears in the sky , while the King of the Netherworld revives from the Original Ener - D Reactor ' s crater . Kuribon appears to Luna , telling her that they mustn ' t let the King reach the Condor geoglyph . As the King begins moving towards it , the Crimson Dragon appears and transports Luna and her companions to Rex Goodwin ' s mansion , where the Condor geoglyph is located . Goodwin stands at the top of the Stairway to the Dragon Star , where he reveals himself to be the final Dark Signer and attaches Roman ' s arm to himself . Goodwin declares that a Shadow Turbo Duel will be held within the Condor geoglyph as a ritual to welcome the King of the Netherworld . As Yusei , Jack , and Crow accept the Duel in order to stop the resurrection of the Underworld Ruler , Luna and the rest of the party cheer for them . However , when " Earthbound Immortal Wiraqocha Rasca " is Summoned , it tries to cheat by Summoning a flock of demonic black birds to attack Yusei , Jack , and Crow . Akiza and Luna are able to provide aid by manifesting " Black Rose Dragon " and " Ancient Fairy Dragon " to fight the horde . Pre - World Riding Grand Prix . Luna has enlisted into the New Domino City Duel Academy along with Leo and Dexter in Maria Bartlet ' s class . After Yusei saves them from being expelled from Duel Academy , she goes missing in the forest were people are reported to disappear . There , she meets Haley and he brings her to his house . Leo goes looking for her while Dexter goes to get Yusei . She is then trapped in the bedroom of Haley ' s sister , Claire . Luna finds out that Claire and Haley are actually dead , while Leo Duels Haley because Haley thinks Leo is going to hurt his little sister . When Yusei arrives , Leo asks Yusei to help Luna and leave him Dueling Haley . Yusei gets in and assists Luna . Luna wants to help the spirit of Claire who is still in the house and finds a special card . Leo defeats Haley and Luna is free . Luna gives Haley the special card and Haley and Claire disappear . She and her brother appear to cheer up Akiza on her first day of riding a Duel Runner , and watch her progress . After that they follow Yusei and Akiza to a skating ring to learn some tricks on how use the Duel Runner . They both comment on whether it is a date or not between the two , and she agrees at some point . When Lester enrolls in Duel Academy , he ' s admired by the students , especially Luna , though her brother suspects something odd about him and tries to keep a distance between him and his sister . Lester invites Luna to his home and shows her how to use a Duel Board . The next day she tries to practice with the Duel Board Lester gave her , and finds her brother practicing as well . Their fun is short - lived as Lester , in his Iliaster uniform , steps in and Duels the two of them , with Luna unable to escape due to her Duel Board moving on its own . At one point in the Duel , Luna was almost blown off the track , but is rescued by Regulus , much to Lester ' s surprise . Lester quickly Summons his newly acquired monster , " Meklord Emperor Skiel " , to fight the twins . Luna Summons " Ancient Fairy Dragon " for the first time and inflicts some damage to Lester . The effect s of " Skiel " absorb her monster . Leo Summons " Power Tool Dragon " , but Lester quickly upgrades " Skiel " and attacks her brother directly , almost killing him , but he ' s saved by the Crimson Dragon at the last second . Luna then proceeds in Dueling Lester . He attacks her directly with " Skiel " , but is protected by the physical attack of " Skiel " with the help of the monsters in her Deck . Lester escaped after the Duel ended . After that , the twins try to seek out Lester but every trace of him disappeared , even the mansion and the memories of anyone else who knew him . World Racing Grand Prix . She , along with Leo , are members of the Team 5D ' s pit crew . Ark Cradle . After the finals of the WRGP , Luna , along with Leo , Bruno , and Akiza , celebrate the victory of Team 5D ' s when the Divine Temple descends from the sky . When they learn from Sherry LeBlanc that Yusei will die if he enters the Temple , Luna cries , stating that she doesn ' t want to lose him . Yusei assures her that nothing will happen to him . She , along with the rest of Team 5D ' s , begin to travel to the Divine Temple . However , the gang gets split into three groups due to Z - one ' s trickery . She travels with Leo and Jack to the center of the temple . Soon after splitting up , Luna , Leo , and Jack come across Aporia , who challenges them to a Duel where after attaching a device to each of their hearts that will tie their Life Points to their lives . Luna and Jack are quickly knocked around by Aporia despite Leo ' s best efforts to protect them . As Luna is barely hanging on by 100 Life Points , Leo soon becomes Aporia ' s new target , unleashing as many card effect s as possible on him . When Luna watches as Leo Summons " Power Tool Dragon " and " Ancient Fairy Dragon " to protect them and is assaulted by the effects of Aporia ' s cards which leads to his death , she begins to cry over Leo , and her Life Points begin slowly dropping due to Aporia ' s device . Leo is then revived by the effect of his " Morphtronic Lantron " and finally awakens as a Signer . He then Summons Life Stream Dragon , which saves Luna and Jack by increasing their Life Points to 2000 with its effect . Luna soon realizes that Leo ' s new dragon is the one she saw in the vision of the 5 , 000 year - old battle she saw . Luna , Leo , and Jack then defeat Aporia with their dragons and head for the Support Gear . After Yusei defeats Antinomy , she , along with Jack and Leo , reunites with Yusei and , inside the Support Gear , finds Z - one . During the battle against Aporia , Aporia himself realised that what he felt was not despair , but hope . Aporia appears in the Support Gear and Duels against Z - one to remind him of such hope . However , he loses . Realizing the power of Z - one ' s Deck and following everyone else ' s example , along with her brother , she gives Yusei her " Ancient Fairy Dragon " in order to help him in the final battle against Z - one . Team 5D ' s future . About half a year after the battle with Z - one , the twins receive a letter from their parents . In it , they tell them that they want to live together , but for that to happen , they may have to leave New Domino City . Luna and her brother are unable to decide what to do because they want to stay with the gang . After Jack challenges Yusei to a Duel and he agrees , the twins along with Akiza and Crow watch the Duel . Leo and Luna end up moving to be together with their parents . In the next eight years , she loses her pigtails , and hangs out with some new friends at a school she attends . Relationships . Leo . Leo and Luna share a very close bond with one another . Leo is the only one be able to reach out to Luna in the Duel Monsters Spirit World , the first time doing it when she was 3 and in a coma in the real world . Leo believed she could still hear him that time , and was able to eventually wake her up . When Luna was brought back to the Spirit world in the present , she didn ' t feel confident enough to protect it , but Leo vowed to protect her , while she protected it , and as a result she resumed her promise . . They also look out for each other and help one another , as shown when Leo takes Luna ' s place Dueling Devack while she was in the Spirit World , and then does what she can after taking over for him . Luna has shown quite a few times that without Leo to support her , she ' d be lost , and has even referred to him as her ' hero ' . Their bond runs so deep that when her brother died against Aporia , she screamed in misery and also began losing Life Points through a weakened heart pulse . As Life Points were tied to the Duelist ' s actual life , it is proven with this that she would literally die without her brother . After Leo awakened as a Signer , Luna cried tears of joy , saying he would always protect her , and calling him her hero while looking at him adoringly . As the gang prepared to part ways , Luna comments on how much Leo has changed , stating that he ' s more of a man now , and referring to him as " big brother " . Ancient Fairy Dragon . The ruler of the Duel Monsters Spirit World found Luna ' s spirit when she lapsed into a coma . Until she woke up , Ancient Fairy Dragon watched over her as if she was Luna ' s guardian angel . Luna vowed to protect the spirit world , but had to forsake that promise . She resumed keeping that promise after her Duel with Professor Frank . After Leo ' s Duel against Sayer , she turned to her for help . When she finally set her free during the Duel with Devack , she thanked Luna for keeping her promise and supported her further in later Duels Lester . Luna showed signs of having a small crush on Lester when he first enrolled at Duel Academy . This included her blushing and looking away flustered when Lester first smiled at her . Her crush on him is further evident , as Yusei pointed out with a slight smile that it was odd for someone like her to be giving someone so much praise like that ) . However it was proven to be short - lived , because after Luna found out that Lester was the one hurting them , she was angry . Yusei Fudo . Yusei has an older brother - younger sibling relationship with the twins . She was initially wary of him because of his criminal mark and his status as an escapee from Satellite . The twins eventually warm up to him and support him . After Luna woke up from her hypnosis by ending the Duel with Professor Frank , she collapsed , and Yusei carried her away from the Dueling platform . Yusei also showed concern for her during her Fortune Cup Duel . When she woke up after the fight with Frank and got out of Yusei ' s arms , she replied she was okay , and Yusei told her to simply do what she wanted in a kind voice . Akiza Izinski . Luna believed Akiza to be misunderstood after using her abilities to " feel " Akiza ' s Deck and was disgusted at the crowd ' s attitude towards her for being a witch . After Akiza develops a bond with the Signers , Luna seems to look up to her as an older sister figure , calling her " Aki - san " . Patty . Patty is Luna ' s friend , usually seen hanging around her . Jack Atlas . Although not as clear as her brother , Luna does seem to hold some respect for Jack . Through the battle with Aporia , it is also evident that Jack to some degree worries for Luna , as her heart weakens , he angrily curses at Aporia for harming such a small child . Decks . Ground . Luna uses a Spirit Deck , mainly relying on defensive tactics through cards such as " Ancient Forest " which severely punishes attack ing . With her Signer Dragon focusing on Field Spell Card s , Luna uses cards such as " Ancient Forest " and " Synchro Monument " to protect her monsters . Other defensive plays include " Fairy Wind " and " Oberon ' s Prank " in combination with " Kuribon " to inflict Effect damage . Turbo . Luna ' s Turbo Deck primarily focuses on her " Ancient Fairy Dragon " , using " Bird of Roses " to acquire its Synchro Material s easily . Luna also uses a Burn strategy through cards such as " Ancient Sunshine " and " Fairy Archer " to inflict large amounts of damage .