The End of the End! - S1.E51

At last MegaMan comes face-to-face with the terrifying Grave VirusBeast that's devouring the entire cyber world... and unless it can be stopped, the network will be destroyed and Mr. Wily will control the world! But it's a losing battle: even AquaCustom Style MegaMan falls before the power of the VirusBeast and is infected with a bug! Then the incredible happens! MegaMan regenerates and emerges in a completely new style: BugStyle! But he gets further infected by the VirusBeast in the process, and now the unstoppable, rampaging monster that's triggering the end of everything is... MegaMan himself!