Tai is now a university student, living alone, working hard at school, and working every day, but with his future still undecided. Meanwhile, Matt and others continue to work on Digimon incidents and activities that help people with their partner Digimon. When an unprecedented phenomenon occurs, the DigiDestined discover that when they grow up, their relationship with their partner Digimon will come closer to an end. As a countdown timer activates on the Digivice, they realize that the more they fight with their partner Digimon, the faster their bond breaks. Will they fight for others and lose their partner? The time to choose and decide is approaching fast. There is a short time before “chosen children” will become adults. This is the last adventure of Tai and Agumon.

Aging samurai Hanshiro Tsugumo arrives at the home of Kageyu Saito and asks to commit a ritual suicide on the property, which Saito thinks is a ploy to gain pity and a job. Saito tells Tsugumo of another samurai, Motome Chijiiwa, who threatened suicide as a stratagem, only to be forced to follow through on the task. When Tsugumo reveals that Chijiiwa was his son-in-law, the disclosure sets off a fierce conflict.

Legend has it that the human race is not the only dominant civilization living on Earth. Two other races exist in this world: the Makai (a demon race) and the Juujinkai (a half-man, half-beast race). Once every 3,000 years, a supreme being known as the “Choujin” (Overfiend) will emerge and bring balance to all three realms on Earth. In present-day Japan, after 300 years of endless searching, a Jujinkai named Amano Jyaku has discovered the presence of the Choujin inside high school slacker Tatsuo Nagumo. But now, Amanoùalong with his sister Megumi and their sidekick Kurokoùmust protect Nagumo and his new girlfriend Akemi Ito from the Makai, who believe that Nagumo is not the Choujin, but an evil entity bent on destroying all living beings on Earth.

Meicoomon vanishes into the distorted abyss. Shaken, Taichi and the others search for answers about Meicoomon’s infection. Kōshirō seeks answers from Meiko but she’s lost all emotion. Kōshirō quarantines Agumon and the other Digimon in the office so that the infection can’t spread any further, but Patamon starts to show signs of the illness. Agumon and the others use Hikari’s voice to tell the team about an important secret concerning the Digital World.

The first story focused on Tai and Kari Kamiya four years before their adventure in the Digital World. It shows their first encounter with Digimon and what happened to them (as well as the other children). Tai and Kari wake one morning to find a Digi-Egg that came out of their computer the night before and the egg soon hatches, revealing a Botamon. The Digimon then evolves into Koromon and then Agumon (not the same one that became friends with Tai in the series, and yet, somehow, both Koromon and Kari remember each other), who then goes out and unintentionally destroys a good part of the neighborhood with Kari riding on his back. A second Digi-Egg appears in the sky to reveal an evil digimon, Parrotmon. Agumon then Digivolves to Greymon but isn’t strong enough to beat Parrotmon and is knocked out. Tai grabs Kari’s whistle and wakes up Greymon, who defeats Parrotmon and disappears with him.