Digimon Chronicle

Digimon Chronicle (デジモンクロニクル) was the storyline accompanying the 2003 Digimon product line. Originally rumored to be a new, full-blown to replace V-Tamer 01, it eventually transpired to be mostly prose text, printed in the booklets which accompanied the "Pendulum X" digital pets. These booklets also contained short six-page manga which covered short excerpts from the story. There are four "chapters", one sold with the Pendulum X 1.0, another with the Pendulum X 1.5, another with the Pendulum X 2.0, and the final chapter with the Pendulum X 3.0. 15 years later, Bandai published a sequel, Digimon Chronicle X.

This fiction tells the story of a Digital World controlled by a sentient computer named. Because had multiplied so much in the past, Yggdrasill, the host computer, was unable to handle the load and the Digital Hazard occurred. Yggdrasill then created the "New Digital World", consisting of three layers for the past, present, and future—Urd, Versandi, and Skuld, respectively, and then let loose with Project Ark and the X Program to eliminate any Digimon Yggdrasill no longer wanted. However, the Digimon adapted by obtaining a program called the X-Antibody, which strengthened them, changed their form, and made them immune to the X Program. Yggdrasill sent in the, thirteen Digimon devoted to keeping order in the Digital World, and at this point Kōta Doumoto, Yūji Musha, and Cool boy, three humans, somehow found their way into the Digital World and met their partner Digimon, for Kōta and  for Yūji. Kōta and Yūji resisted Yggdrasill and the Royal Knights, but Cool boy apparently sided with Yggdrasill.