Release date: August 3, 2000
Price: 3800 yen
Genre/System: Collection RPG, Wonderswan
In the summer of 2000, Ryo was visiting with Ken when they witnessed the Metal Garurumon and WarGreymon versus Diablomon battle from the movie "Bokura no Wargame". After a mild panic attack, Ryo decides to send good-luck e-mail to Taichi and Yamato. Metal Garurumon and WarGreymon fuse into Omegamon and take out Diablomon, and Taichi thanks everyone for their encouragement. Later, V-mon arrives and tells Ryo and Ken that they're needed in the Digital World and a D-3 is given to Ryo.
Once in the Digital World, Ryo is sent to the mountain on which Diablomon retreated and finds, once Diablomon was defeated, that it was nothing more than a lure set by Millenniumon to drag him back to the Digital World. Millenniumon says that he was waiting for Ryo's return and that all this was plotted. He then laughs evilly and causes the mountain's explosion. This explosion rips the Digital World into two. Thus separated, Ryo and Ken have to fend for themselves.
During his travails, Ken meets up with Wormmon and, with the aid of the Reload Machine that allows him and Ryo to communicate and trade items across the dimensional rift, proceeds on a tag-team-like quest to undermine Millenniumon's powers once again. Along the way they find pieces of digimentals to stick back together and train their digimon.
As all these games must lead to eventually, the heroes take on Millenniumon. Millenniumon reveals that he cannot be defeated by just one power, so Ryo and Ken must work together to defeat him. It should be noted that Millenniumon is extremely rude to Ken, but treats Ryo as an equal. The final battle is undertaken in a world created from Millenniumon's mind, and when he is defeated, Millenniumon's physical body is destroyed. Shortly after, he releases his Dark Seeds. Ken pushes Ryo out of the direct line of fire and gets one in the neck instead. As Millenniumon's body collapses, he claims that his power too is eternal.
The game flash-forwards to Gennai's house, where Ken is unconscious and everyone has gathered around him. Wormmon narrates the ending, saying that Ken became increasingly cold to him and he believes Ken will become gentle again. Wormmon swears to protect Ken.
After the credits roll, there is a flash forward to the future, in which the Kaiser stands with his back to the player, on a cliff overlooking the Dark Ocean. He says that he has returned to this world to show that he is different from Millenniumon. He is the Digimon Kaiser.