Agumon

Agumon is a Reptile Digimon. It has grown up and become able to walk on two legs, and has an appearance like a tiny dinosaur. Because it is still on the way to adulthood, its power is low, but as its personality is quite ferocious, it doesn't understand fear. It has grown hard, sharp claws on both its hands and feet, and demonstrates its power in battle. It is also a being that foretells Digivolution to a great and powerful Digimon.

Agumon first appears as a Digi-Egg in Tai and Kari Kamiya's computer, which then appears in real life and hatches as a Botamon. It then digivolves into Koromon and then Agumon, who runs around the city with Kari. Parrotmon then appears and the big Agumon digivolves to into Greymon and fights it, though both are sucked back into the Digital World before the fight can be completed.

Agumon is then either chosen or created, along with the rest of the DigiDestined's Digimon, as part of a project to help control the balance between good and evil in the Digital World. When he is a Digi-Egg again, this time connected to Crest of Courage, the Dark Masters attack the facility where he is housed, and Gennai flees with the eggs in hand. He is taken to File Island, where he hatches into Botamon who eventually digivolves into Koromon. During this time, he plays with the other Digimon as he holds the Digivice that belongs to Taichi "Tai" Kamiya, waiting for his partner's arrival. One day, the Digivices suddenly vanish into the sky, heralding the coming of their partners.

Koromon discovers his partner, Tai, after he comes to the Digital World unconscious. Introducing himself, Koromon sticks by Tai despite his confusion and eventually meets up with Koushiro "Izzy" Izumi and Motimon until a Kuwagamon attacks them. Hiding in a tree to escape, the four eventually meet up with the rest of the DigiDestined, who attend the same summer camp as Tai and Izzy: Sora Takenouchi and Yokomon, Yamato "Matt" Ishida and Tsunomon, Mimi Tachikawa and Tanemon, Joe Kido and Bukamon, and Takeru "T.K." Takaishi and Tokomon. Unfortunately, Kuwagamon attacks them once more but Koromon, alongside the other Digimon, digivolves to his Rookie form to protect his partner and becomes Agumon. Though strong, Kuwagamon is still stronger, and they are thrown off a cliff.

Gomamon rescues them from drowning and the group ends up at a beach. Here, the DigiDestined discuss their food supply, and Agumon is the only one to eat in this time frame. Because Agumon is the only one to eat, he is the only one who has energy to battle the Shellmon who attacks, but he isn't strong enough to successfully fend him off. In order to help, Tai decides to provide a distraction. He is caught while doing so, and the rush of anger and protectiveness that Agumon feels spurs his Digivolution into the Champion form Greymon, who defeats Shellmon.

Agumon returns to Primary Village in time to protect T.K., Matt's little brother, from Leomon as Greymon. They subsequently defeat Devimon and are told by Gennai to head to the Server Continent. Along the way, the group finds the Tags to their Crests but are attacked by Etemon on the Continent itself. The DigiDestined manage to escape into a tunnel, where Tai finds his Crest of Courage. This brings Tai arrogance, however, as well as the ambition to get Agumon to digivolve into Ultimate. Despite his efforts to cool Tai down, Agumon suffers as Tai overfeeds him in order to give him energy. When Etemon traps them in an arena against another Greymon and Agumon digivolves to fight, he is beaten because his reaction times are so slow due to the food. Tai walks deliberately into trouble, knowing that danger is what causes their partners to digivolve, but it has the wrong effect: Greymon dark digivolves to SkullGreymon, who rampages around and takes out Garurumon, Birdramon, and Kabuterimon before regressing into an exhausted Koromon. As a result, both of them lose their confidence until Piximon arrives and forces them to face their doubts. Agumon views a time when Tai tried to learn how to ride a bike, and learns that he needs to bounce back after suffering from a defeat that despite all the hardship, all of the pain, he needs to come back after suffering defeat.

Agumon continues to support Tai as they discover Etemon's main base of operations. When Tai finally discovers what Courage truly is, he walks alongside his partner as they aim to take on Etemon fused with his Dark Network Tai's unflinching courage causes his Crest to shine, and Agumon digivolves to his Ultimate form MetalGreymon. MetalGreymon defeats Etemon, but Etemon's massive energy causes a dimensional rift to open, which Tai and MetalGreymon are sucked into.

The warp leads back to the Real World, and Agumon has dedigivolved to Koromon during the transfer. Koromon follows his partner home and relaxes for a bit while taking care of his little sister Kari Kamiya, who seems to recognize him as Koromon, as she, though they do not remember, have met Koromon before. Tai soon realizes that not only has little time passed but also that his friends haven't returned. Digimon then begin appear, though only he and his sister can see them. When Tai receives a warning from Izzy to not come back, Koromon becomes restless. Digivolving to Agumon and defeating an Ogremon, a dimensional warp opens. Agumon knows he must return and eventually convinces Tai to return as well, despite leaving his little sister behind.

Upon their re-entry, Agumon finds the group in severe disarray. Time moves much quicker, and months have passed in the Digital World though only hours have in the Real World. The entire team has gone their separate ways to pursue their own ideas for finding Tai and Agumon. Tai and Agumon first locate T.K., who has been left alone by the rest of the group, and manages to convince him to reconcile with his partner, Patamon, rather than be manipulated by DemiDevimon. With T.K. and their partners, Tai leads them to a diner, where they find Matt and Joe and rescue them from Digitamamon. Agumon and Tai join Joe and Gomamon in searching for the others and find Mimi, managing to convince her to leave her princess life with the Otamamon and Gekomon.

By now, Myotismon has emerged as the next great threat, and he is in search of the eighth DigiDestined child. The DigiDestined pursue him to the Real World through Myotismon's special gate. Throughout this time, Tai manages to hide Agumon from his family except Kari, who continues to recognize him. When Gatomon is captured and Myotismon stages an all out attack to round up all the children to force Gatomon to find her partner, he and Greymon whisk Kari to safety, though they are unable to save his parents. Entrusting Kari to Matt, Tai and Greymon attempt to rescue the trapped citizens, though they only manage to make it in time to regroup with the DigiDestined in a final assault on Myotismon.

After Myotismon is first defeated due to Wizardmon's sacrifice, Myotismon instead digivolves to VenomMyotismon. The DigiDestined believe that the key to defeating VenomMyotismon is to have Angemon and Angewomon shoot Tai and Matt with arrows of hope and light. Both of them agree, and Agumon and Gabumon warp digivolve into WarGreymon and MetalGarurumon, Mega Digimon who, with help, manage to defeat VenomMyotismon. Thinking that it is finally over, the group is shocked to see the Digital World appear in the sky. The DigiDestined and their partners decide to go back to protect both worlds they love. All of them open another warp and go back to the Digital World to restore the balance.

The Dark Masters emerge as the major enemy, and it is revealed that they were the ones who warped and rebuilt the Digital World. Upon their return, Agumon is handily defeated even as WarGreymon, and it is only through the agency of Piximon, who tells the group that they must become strong, that they are able to escape the immediate situation. It is through his sacrifice that they are able to flee entirely. Tai takes this to mean that they must become physically strong, and he orders the group to defeat a Shellmon, whom they previously needed to digivolve to beat. Izzy discovers his that his WarGreymon form is equipped with "Dramon Destroyers" able to easily slay Dramon-type Digimon, like the Dark Master MetalSeadramon they are up against. Agumon digivolves to WarGreymon to fight him, but he is being defeated. Under Pressure Through Whamon's sacrifice, WarGreymon defeats MetalSeadramon.

In the Dark Master Puppetmon's forest, Agumon is rendered nearly useless by Puppetmon's manipulations, but T.K. manages to free them from Puppetmon's control. As MetalGreymon, he manages to defend the group from attacking Garbagemon up until Matt and MetalGarurumon save them. Tai's desire to continually move forward is at odds with Matt's need to mourn their lost, and that along with Cherrymon's manipulations culminate in Tai and Matt getting into a fistfight as WarGreymon duels with MetalGarurumon. Their battle ultimately causes a rift in the friends. Matt leaves to reevaluate his place in the group, while Mimi can't deal with the drama and the fighting and strikes off on her own, while Joe goes with her to make sure she is safe. The group are attacked by Puppetmon and his RedVegiemon army, but they manage to drive him off.

While split, Kari falls ill, and Tai frantically searches for a cure for his sister, not knowing that it is the Dark Master Machinedramon's domain. Though weakened by battle, Koromon is empowered by Kari's light to digivolve to WarGreymon and defeat Machinedramon once and for all.

About to fight Piedmon, they are met by his vanguard LadyDevimon. Agumon wishes to fight, but Tai, with all of his personal growth, doesn't allow it. He, looking ahead, has MegaKabuterimon and Angewomon take care of it to allow Agumon to save his strength for Piedmon. Tai and WarGreymon manage to hold the line against Piedmon until Matt returns, and the two reconcile, with Matt's Crest of Friendship healing WarGreymon's wounds. Unfortunately, Piedmon proves to be too strong and captures him, Matt, and their partners by turning them into keychains. MagnaAngemon, Patamon's Ultimate form, saves them, and they manage to defeat Piedmon, only for Apocalymon to appear.

Apocalymon turns out to be a formidable foe, destroying their Crests and managing to turn them into free-floating data. Agumon tells the group to not give up and, bonding with Tai, declares that they are invincible together. Tai discovers that the Crest of Courage lies within him, and uses that power to digivolve Agumon to WarGreymon and return to normal. All together, the group defeats Apocalymon, with WarGreymon launching a Terra Force directly into his main body.

Unfortunately, the solar eclipse marks the rebirth of the Digital World. In the English version, it is thought that the gate would never reopen, stranding the DigiDestined in the Digital World, while the Japanese version has the reasoning that the Digital World might see them as foreign elements as it tries to recover and might delete them. Either way, the DigiDestined must leave their partners. Tai and Agumon reminisce at the spot where they fought Seadramon, joking and ribbing at each other.

At that point, Agumon, along with the other partner Digimon, wave goodbye to their partners as they take a trolley back home.