The second series follows the events of the second game focusing on the lost continent of Mu. The ancient civilization vanished ages ago, and a few of its remnants still exist as myths and legends called UMAs (Unidentified Mystery Animals similar to FM-ians that also have the ability to fuse with humans). The UMAs begin merging with humans in order to search for the treasures of Mu, the powerful OOPArts, which will give them the power to revive Mu. After Geo and Omega-Xis encounter several unusual enemies, they meet a professor named Doctor Vega who sends them on a quest to find the OOPArts and stop the UMAs. Using the OOPArts, Mega Man is able to take new forms, primarily the sword-wielding Thunder Zerker form. Near the end, Geo discovers that Doctor Vega and her accomplice Hollow are manipulating Geo to use the OOPArts for the revival of Mu and the devastating force known as Le Mu. But Mega Man combines the three OOPArts together, forming Tribe King, and uses this new power to stop Le Mu and seal Mu once more.