Digimon Chronicle served as the narrative backdrop for the 2004 Digimon merchandise line. Initially rumored to be a new, full-scale manga intended to replace V-Tamer 01, it ultimately turned out to be primarily prose text, printed in the booklets that came with the "Pendulum X" digital pets. These booklets also featured short, unrelated six-page manga segments. The story is divided into four "chapters": one was sold with the Pendulum X 1.0, another with the Pendulum X 1.5, a third with the Pendulum X 2.0, and the final chapter with the Pendulum X 3.0. The fiction recounts a Digital World governed by a scientist computer named Yggdrasil. Due to the massive multiplication of Digimon in the past, Yggdrasil, the host computer, could not manage the load, resulting in the Digital Hazard. Yggdrasil subsequently created the "New Digital World," comprising three layers representing the past, present, and future—Urd, Versandi, and Skuld, respectively—and then initiated Project Ark and the X Program to eliminate any Digimon Yggdrasil no longer desired. However, the Digimon adapted by acquiring a program known as the X-Antibody, which strengthened them, altered their forms, and rendered them immune to the X Program. Yggdrasil deployed the Royal Knights, thirteen Digimon dedicated to maintaining order in the Digital World. At this juncture, three humans—Kouta, Yuuji, and Shinji—somehow entered the Digital World and encountered their partner Digimon: Dorumon for Kouta and Ryuudamon for Yuuji. Kouta and Yuuji opposed Yggdrasil and the Royal Knights, whereas Shinji apparently sided with Yggdrasil.