Kaigaku

**Kaigaku** (獪 (かい) 岳 (がく) , *Kaigaku*?) is a supporting antagonist in the Infinity Castle Arc of *Demon Slayer: Kimetsu no Yaiba*. He is a demon affiliated with the Twelve Kizuki, holding the position of **Upper Rank Six** (上 (じょう) 弦 (げん) の陸 (ろく) , *Jōgen no Roku*?), replacing Daki and Gyutaro after their deaths.

Kaigaku was a former Demon Slayer and Zenitsu Agatsuma's senior disciple under the former Thunder Hashira (鳴 (なり) 柱 (ばしら) , *Nari Bashira*?), Jigoro Kuwajima. However, sometime during Hashira Training, Kaigaku went on a mission and encountered Upper Rank One, Kokushibo, quickly surrendering to him to save his own skin and later becoming a member of the Twelve Kizuki.

## Appearance

As a human, Kaigaku is a muscular young man of average height who has short, spiky black hair, with two thick strands framing his face, and a pair of dull, cold turquoise eyes framed by thick, arched eyebrows. He has an unfriendly face, that is always set in a semi-permanent snarl.

After becoming a demon, he gains many demonic traits like four black flame-like markings on both sides of his cheeks, elongated canines that resemble fangs, sickly pale skin, sharp blackened nails, and pointed ears. By becoming a member of the Twelve Kizuki and rising to the position of Upper Rank Six, his eyes are etched with the kanji of "Upper Rank" (上 (じょう) 弦 (げん) , *Jōgen*?) and daiji of "Six" (陸 (ろく) , *Roku*?).

When he was still human, who is still undergoing training under Kuwajima, he is shown to be wearing a black kimono with a white collar, worn loosely to expose his chest and his signature magatama-necklaces around his neck. When he became a Demon Slayer, he wore the Corps' standard uniform consisting of a black *gakuran*-like jacket, a pair of equally black tattsuke-hakama pants held up by a white belt, tucked into white kyahan wrapped around his ankles, and a pair of tabi socks and zori.

When he became a demon, he is shown to be wearing his signature kimono secured with a blue obi over his Demon Slayer uniform that has yellow flame-like markings near the chest area. His forearms are seemingly wrapped in *kyahan*-like material. He also wears multiple necklaces on his neck and wrist with green colored strings that hold together blue magatama-like pendants that were yellow in color when he was human.

### Gallery

Kaigaku's appearance when he was a child.Kaigaku's appearance as a Demon Slayer.
## Personality

Though outwardly brash and arrogant, Kaigaku is in fact cowardly and selfish. Like many orphans living on the streets, he grew up resorting to thievery and other immoral means to survive. He even goes so far as to sacrifice the lives of all the orphans under Gyomei's care to save his own skin. This has caused him to develop an intense form of self-preservation, often doing what in his own best interest at the expense of others.

At some point after this, Kaigaku met and became the disciple of Jigoro Kuwajima. Because of his great talent with a sword, he was poised to become the next Thunder Hashira. However, unlike other orphans who join the Corps, Kaigaku never developed a desire to slay demons or protect people. When confronted with a stronger opponent, Kaigaku quickly surrendered. Furthermore, he seems to have developed a sense of hypocritical self-righteousness. He called Zenitsu Agatsuma worthless for having no dignity or perseverance and was repulsed at the idea of succeeding Jigoro along with him. Kaigaku also seems to have a twisted perspective of 'right' and 'wrong', believing that those who judge him right (i.e., say he is worthy) are good and those who judge him wrong and have a low estimation of him are evil. Additionally, he also has an inflated ego, viewing himself as a special and gifted person.

In the end, after being beheaded and being at death's door, Kaigaku remains unrepentant and is pleased to know that at least Zenitsu would die with him. However, Yushiro arrives and begins mocking him that he will be given nothing since he never learned how to give, and Kaigaku's fate was sealed once he decided to let his desire inflate and take control of him. Upon seeing Yushiro rescue Zenitsu, Kaigaku screams in anger as the remainder of his body disintegrates.

## History

Kaigaku was an orphan and a thief who had to eat scraps and steal to survive. He was one of the orphans Gyomei Himejima cared for at his temple. After he was caught by the other children for stealing temple money, he was chased out at night and encountered a demon, which he then let in to the temple in exchange for having his life spared.

Kaigaku developed the belief that strength and survival were the only things worth respecting and was willing to grovel and beg for his life if it was what it took to survive. Eventually, he was taken in by Jigoro along with Zenitsu, learning Thunder Breathing. He became determined to become Jigoro's successor and the new Thunder Hashira. Jigoro, however, insisted that both he and Zenitsu would become his successors, despite Zenitsu's weakness and timid nature.

## Synopsis

### Mount Natagumo Arc

During his battle against Son of the Spider Family. Zenitsu recalls a moment during in his training when Kaigaku had admonished him for wasting the time of Jigoro, who he had respected, because of his constant whining and cowardice. When he called their trainer "*Gramps*", Kaigaku threw a peach at him and demanded he never attempt to act familiar with him.

### Hashira Training Arc

During Hashira Training, Zenitsu receives word that Kaigaku had become a demon, and that Jigoro committed seppuku as atonement. Kaigaku had the unfortunate luck of encountering Kokushibo, and, upon witnessing the Upper Rank's immense power, kneeled before him and surrendered in order to save his own skin. Kokushibo offered the Demon Slayer a chance to become a demon and gave him a handful of Muzan's blood to intake, believing if Muzan believes him to be worthy, he can join the Twelve Kizuki. Despite fear consuming his body, Kaigaku eventually obliged and drank the demon's blood, transforming him.

Even in the short time he was a demon, Kaigaku had already eaten numerous people, and eventually became powerful enough to take his position as the new Upper Rank Six of the Twelve Kizuki.

### Infinity Castle Arc

During the Demon Slayer Corps attack on the Infinity Castle, a hidden Kaigaku is detected by Zenitsu and forced to show himself. Kaigaku dismisses his fellow trainee's commanding tone, claiming it was improper manners to speak to a senior in such a way, but Zenitsu tells him that now that he is a demon, he does not recognize him as so. Kaigaku mocks the Demon Slayer for still only using Thunder Breathing's first form but is taken aback when Zenitsu insults his spot as Upper Rank Six as a vacant position at the bottom of the ranks. Zenitsu then angrily told him of Jigoro's agonizing death, as he had committed seppuku to atone for his transformation but no one was there to finish the task, leaving him to die alone.

To this, the unrepentant Kaigaku only laughs in his face and claims only he had valued who he is, believing that Jigoro never saw his worth for attempting to place him in the same position as "scum" like him. Zenitsu then retorts that if he was as pathetic as he made him to be, then so would he since Jigoro saw them as equals. Angered, the new Upper Rank Six responded by attacking him with **Thunder Breathing, Fourth Form: Distant Thunder**. To Kaigaku's shock, Zenitsu blitzes past him and slices into his neck, shocking the Upper Rank as he did not expect Zenitsu to change so drastically.

Recalling his encounter with Kokushibo and reaffirming his belief that everything he did to live was in the right, Kaigaku then focuses his anger on Zenitsu and attacks him with **Thunder Breathing,** **Second Form: Rice Spirit**. Zenitsu is shocked to see consecutive attacks and believes Kaigaku had eaten much victims. He then uses **Third Form: Thunder Swarm** and successfully hits Zenitsu, before attacking again with **Fifth Form: Heat Lightning** to strike Zenitsu with his lightning. As Kaigaku revels in his new power, he attacks again with **Sixth Form: Rumble and Flash**, severely wounding the Demon Slayer and causing him to fall.

Watching Zenitsu's body plummet down the castle, Kaigaku claims he is different to him. To his utter shock, the demon sees him land upright along the walls and is suddenly attacked with **Thunder Breathing, Seventh Form: Honoikazuchi no Kami**, instantly decapitating him. Unable to see the attack, he curses Jigoro for teaching Zenitsu an unknown move, to which Zenitsu tells him the form was something he created to use alongside him.

As his severed head and Zenitsu's unconscious body fall, Kaigaku is taken aback by Zenitsu's creation of a seventh form, and he can only grumble at the thought of someone weaker than him attaining such a feat. As he burns to ash, Kaigaku refuses to accept he had lost to Zenitsu, reassuring himself that with Zenitsu no longer having any strength remaining, he will die with him. A demon enters his view and tells him that someone who never gives can never receive, and that wanting is the same as nothing when one cannot make it himself, before telling Kaigaku that dying alone is pitiful. As Kaigaku disintegrates completely, the demon catches Zenitsu and leaps to safety, denying the new Upper Rank Six's revenge on his killer.

## Abilities

### Overall Abilities

As a transformed Demon Slayer and a member of the Upper Ranks, Kaigaku was an extremely powerful demon. This is supported by the fact that he had to receive a lot of Muzan Kibutsuji's blood for him to turn into a demon as users of Total Concentration Breathing are more resistant to the effects of the Demon King's blood. Zenitsu also noted that Kaigaku had eaten a lot of humans in the short period of time between Hashira Training and his encounter with him, further testifying his strength.

According to Yushiro, during Kaigaku's short tenure as Upper Rank Six, he has yet to master his techniques and abilities and could have killed Zenitsu immediately in a year's time.

### Physical Abilities

**Immense Speed & Reflexes:** As a Thunder Breathing user turned Upper Rank demon, Kaigaku possesses tremendous movement speed and reflexes due to the Thunder Breathing swordsmanship style placing a heavy emphasis on swiftness and bursts of speed. This combined with assimilating a large amount of Muzan's blood makes Kaigaku an extremely fast fighter, as shown when he could more than keep up with Zenitsu Agatsuma, a seasoned and skilled Demon Slayer that had trained under the same teacher to learn the same Breathing Style, and even overpower him for the majority of their clash.

## Fighting Style

**Master Swordsman:** As the one who was initially supposed to inherit Jigoro's position as the Thunder Hashira, it is implied that Kaigaku is an extremely proficient swordsman with great skill in Thunder Breathing. His swordsmanship is different compared to most Demon Slayers as he places his sword sheath at his back rather than on either side of his waists. Nonetheless, his swordsmanship skill could match that of Zenitsu who had previously fought Upper Rank demons. With his Blood Demon Art, Kaigaku's swordsmanship was greatly enhanced and became even more dangerous.

### Breathing Style

**Thunder Breathing** (雷 (かみなり) の呼 (こ) 吸 (きゅう) , *Kaminari no kokyū*?): A Breathing Style Kaigaku learnt from a former Hashira, Jigoro Kuwajima. It was implied Kaigaku was quite talented in learning this Breathing Style, so much so that Jigoro wanted Zenitsu to emulate him. But despite this, Kaigaku was unable to learn the first and most fundamental form of Thunder Breathing, **Thunderclap and Flash**, despite being able to learn and master all other 5 techniques of this Breathing Style. Still, some Demon Slayers said that because of Kaigaku's inability to master the first form, the other 5 techniques he learnt wouldn't amount to much.

After becoming a demon and developing a Blood Demon Art, Kaigaku's Thunder Breathing has manifested into reality as he can manipulate actual lightning and electricity, greatly improving the offensive power of this Breathing Style. Kaigaku even stated that he has "surpassed Thunder Breathing".

### Blood Demon Art

**Electrokinesis:** Complementing his Breathing Style, Thunder Breathing, Kaigaku's Blood Demon Art grants him special electrokinetic abilities which allow him to generate and manipulate black colored lightning and electricity from his flesh and blood. This lightning-like Blood Demon Art creates a special effect which cracks and rends his target's flesh while burning it, greatly augmenting the lethality and offensive capability of his attacks. The bleeding caused by Kaigaku's sword effect nearly destroyed Zenitsu's eyeballs and left him severely injured after the fight.

Kaigaku uses this Blood Demon Art to great effect, utilizing lightning in conjunction with his Thunder Breathing techniques to enhance his attack range and speed, which even Zenitsu had trouble keeping up with. It is implied that this Blood Demon Art helped make up for Kaigaku's own inability to perform the most fundamental technique of the Thunder Breathing style, **Thunderclap and Flash**.

### Techniques

* Description
* Demonstrations

* **Second Form: Rice Spirit** (弐 (に) ノ型 (かた) 　稲 (いな) 魂 (だま) , *Ni no kata: Inadama*?) - Kaigaku releases five arched slashes accompanied by lightning in quick succession.

* **Third Form: Thunder Swarm** (参 (さん) ノ型 (かた) 　聚 (しゅう) 蚊 (ぶん) 成 (せい) 雷 (らい) , *San no kata: Shūbun Seirai*?) - Kaigaku surrounds the enemy with waves of arched lightning and attacks them from all directions.

* **Fourth Form: Distant Thunder** (肆 (し) ノ型 (かた) 　遠 (えん) 雷 (らい) , *Shi no kata: Enrai*?) - Kaigaku generates a ball of electricity that releases waves of strong multi-directional lightning bolts from afar.

* **Fifth Form: Heat Lightning** (伍 (ご) ノ型 (かた) 　熱 (ねつ) 界 (かい) 雷 (らい) , *Go no kata: Netsu Kairai*?) - Kaigaku unleashes a long-ranged upward sword slash accompanied by lightning.

* **Sixth Form: Rumble and Flash** (陸 (ろく) ノ型 (かた) 　電 (でん) 轟 (ごう) 雷 (らい) 轟 (ごう) , *Roku no kata: Dengō Raigō*?) - Kaigaku releases a series of powerful long-ranged lightning attacks that strike his opponent from afar.

## Equipment

**Flesh Katana:** Similar to the demon who would transform him, Kokushibo, Kaigaku carries around a modified version of the Nichirin katana he used when he was a Demon Slayer that is made from his flesh and blood. However, unlike Kokushibo's katana, his katana isn't heavily distorted and is nearly identical to his original one. His flesh katana has a black lightning pattern on both sides of his yellow tinted blade along with a black and gold handle. Kaigaku's katana has a tsuba identical to the one used by Zenitsu Agatsuma, which is circular shaped with four slight indentations, the center has a silver tone with small triangles and has a golden border. It is implied that his flesh blade facilitates the use of his Blood Demon Art, as he can channel his blood through it when he unleashes his techniques. Unlike most swordsmen, Kaigaku places his sword sheath on his back instead of by his waist.

## Battles

Kaigaku Battles

**Infinity Castle Arc**

* Zenitsu Agatsuma vs Kaigaku

## Trivia

* His given name, **Kaigaku**, is composed of the Kan-on'yomi reading of the kanji for both "sly, cunning, crafty" (獪 (かい) , *kai*?) and "tall mountain, mountain peak" (岳 (がく) , *gaku*?).
	+ His surname in the Kimetsu Academy, **Inadama**, is composed of the Kun'yomi reading for "the rice plant Oryza sativa" (稲 (いな) , *ina*?) along with the rendaku for "gem, jewel" (玉 (だま) , *dama*?).
* Because of the movement pattern of the Thunder Breathing's first form, it can be speculated that one reason he had difficulty mastering it was because he placed his scabbard/sheath on his back instead of either side of his waist.
* Kaigaku is the second known Demon Slayer to have become a demon, the first being Kokushibo.
* Kaigaku's necklace and bracelets are Taijitu/magatama (tomoe) symbols. Before he transforms into a demon, the symbol is yellow (good, enlightened), and it turns blue (bad, darkness, depth) after he becomes one. The fractured magatama itself seems to represent his broken and unstable mentality.
* Kaigaku ranked 21st place in 2nd character popularity poll with 865 votes.
* Kaigaku received a kimono from Jigoro Kuwajima, his sensei, identical to the one he himself wore, but Kaigaku never wore it once.

## Quotes

* (To Zenitsu Agatsuma) "*"Gramps"? Don't speak of him in that familiar way! Sensei is a former Hashira! Someone who earned the highest title in the Demon Slayer Corps! Almost no one ever gets the chance to be trained by a former Hashira! The time Sensei spends training you is all for nothing! You're an eyesore, okay? Get out of my sight! Why are you here? Why do you insist on clinging here?*"
* (To Zenitsu Agatsuma about his teacher) "*I don't care! So what? Are you saying I should be sad? That I should repent? I don't care about anyone who doesn't value me! At every moment I always serve those who know my value!*"
* "*There is no shame in kneeling before someone in overwhelming strength. As long as you stay alive, it will work out somehow. Until you die, you haven't lost. You may rub your face in the dirt... you may lose your home or drink muddy water... people may curse you for stealing money... but as long as you live on... you can win someday. You will win. I have moved forward with that belief.*"
* (To Zenitsu Agatsuma about good and evil) "*Those who correctly evaluate me and know my value are good! Those who have a low estimation of me are evil!*"

## References

1. ↑ *Kimetsu no Yaiba* Manga: Volume 13, (Extra Pages).
2. ↑ 2.0 2.1 2.2 *Kimetsu no Yaiba* Second Fanbook.
3. ↑ 3.0 3.1 3.2 3.3 *Kimetsu no Yaiba* Manga: Chapter 145 (Page 2-3).
4. ↑ *Kimetsu no Yaiba* Manga: Chapter 135 (Page 13).
5. ↑ 5.0 5.1 5.2 *Kimetsu no Yaiba* Manga: Chapter 145 (Page 8).
6. ↑ *Kimetsu no Yaiba* Manga: Volume 17, (Extra Pages).
7. ↑ *Kimetsu no Yaiba* Manga: Chapter 34 (Pages 4-5).
8. ↑ *Kimetsu no Yaiba* Manga: Chapter 145 (Page 4).
9. ↑ 9.0 9.1 *Kimetsu no Yaiba* Manga: Chapter 145 (Page 7).
10. ↑ *Kimetsu no Yaiba* Manga: Chapter 146 (Page 9).
11. ↑ *Kimetsu no Yaiba* Manga: Chapter 125 (Page 5).
12. ↑ 12.0 12.1 *Kimetsu no Yaiba* Manga: Chapter 145 (Page 11).
13. ↑ *Kimetsu no Yaiba* Manga: Chapter 144 (Page 16).
14. ↑ *Kimetsu no Yaiba* Manga: Chapter 145 (Page 13).
15. ↑ *Kimetsu no Yaiba* Manga: Chapter 145 (Page 9-11).
16. ↑ *Kimetsu no Yaiba* Manga: Chapter 146 (Page 8-9).
17. ↑ *Kimetsu no Yaiba* Manga: Chapter 145 (Page 11-13).
18. ↑ *Kimetsu no Yaiba* Manga: Chapter 144 (Page 17).
19. ↑ *Kimetsu no Yaiba* Manga: Chapter 145 (Page 9).
20. ↑ *Kimetsu no Yaiba* Manga: Chapter 145 (Page 10).
21. ↑ *Kimetsu no Yaiba* Manga: Volume 17.
22. ↑ *Kimetsu no Yaiba* Anime: Episode 17.
23. ↑ *Kimetsu no Yaiba* Manga: Chapter 144 (Page 14).