Digimon: Operation Overdrive

Digimon Digital Monsters  (デジモンアドベンチャー, Dejimon Adobenchā ? ) is a Japanese animated television series created by Akiyoshi Hongo and produced by Toei Animation based on the Digimon virtual pet made by Bandai and is the first anime installment in the Digimon media franchise. The series is continued with the same characters in Digimon Adventure 02.

The planning for Digimon Adventure started in 1998 and was done in cooperation by Toei Animation, Bandai and Fuji Television.

Plot
Long ago, a group of ten Digimon sacrificed themselves to defeat an ultimate evil that threatened the Digital World. These Ancient Warriors created artifacts from their data, the twenty "Spirits" (ten Beast spirits and ten Human spirits, one of each for each element), before leaving the Digital World in the care of the three Celestial Digimon. However, one of the three, Cherubimon begins a reign of terror. To counter this, the Celestial Digimon Ophanimon summons five children from the human world into the Digital World via the train-like Trailmon. There, these five Digi-Destined find their respective Human Spirits and "Spirit Evolve" into Digimon, the Legendary Warriors. However, while finding their respective Beast Spirits, the five find themselves hunted by five other Legendary Warriors that serve Cherubimon (for five of these spirits were given to the care of Cherubimon before his corruption).

After they defeat four of them (JP destroys one, another loses his Beast Spirit to Koji and is destroyed by Duskmon for being useless, Zoe destroys another and Takuya destroys the last one), Koji Minamoto discovers that Duskmon, the fifth evil Legendary Warrior, is really his twin brother Koichi Kimura. With Takuya Kanbara's help, Koji is able to free his brother, and Kouichi restores the Spirits of Darkness to their true forms and joins the team as the true Warrior of Darkness, Löwemon.

After they defeat Cherubimon, who is killed by Takuya as EmperorGreymon, the DigiDestined learn that the true mastermind was the very evil the Ancient Warriors sealed away within the Digital World's core, Lucemon. So now the six DigiDestined must try to defeat the two Royal Knights who were sent by Lucemon to scan all of the Digital world's data to complete his rebirth. Ultimately Takuya and Koji succeed in defeating the Knights, but not before they destroy and scan the whole digital world and free Lucemon (who scans the Royal Knights after the DigiDestined defeat them, allowing him to evolve to a more powerful form than he was before). At this point, after defeating Takuya and Koji as EmperorGreymon and MagnaGarurumon, Lucemon destroys the Digital World's moons. He then began opening a portal to the real world: a portal that leads to the underground train station in which the DigiDestined were brought. He is confronted by the Digidestined who try to attack him with a mutli hit tactic, fighting together as a complete team. However Lucemon ends up killing Koichi (who sacrificed himself to save the others). Forming the ultimate Legendary Warrior Digimon Susanoomon by combining all the spirits in Takuya and Koji, Lucemon is defeated and scanned. However, all of his evil transforms into another form of Lucemon, one of pure evil, which tries to go to the real world. Having almost given up, the spirits of the Ten Legendary Warriors come to life, along with the spirits of Ophanimon, Cherubimon and Seraphimon, giving the kids new hope. Together, they all form a seemingly more powerful Susanoomon, and defeat and ultimately destroy Lucemon (at least the evil part of Lucemon) once and for all, giving the Digital World its data back, ultimately restoring its true form. The children go back to the real world and find that an hour hasn't even passed since they left (only a 1/2 hour at most). They find Koichi, who they discover was only in the Digital World for having been in a coma for falling down a flight of stairs. He then wakes up when Koji arrives, leading everyone into living happily ever after, having the events of the Digital World change them forever.