Mega Man along with Roll set forth to find the four Keys in the Manda, Nino, Saul Kada and Calinca Ruins, while battling the Pirates, most often the Bonne Family, along the way. When Mega Man returns with the final key to the Sulphur Bottom, Sera orders Geetz to attack the ship and take the keys. Yuna appears in the ship and orders Gatz to fight Geetz. Mega Man stumbles upon Yuna, who then gives some reminder about his former life and explains to him the terrible catastrophe she was trying to prevent: Sera's plans for the execution of the "Carbon Reinitialization Program", meant to kill every human from Terra and revive the original humans. Soon after, Mega Man reaches the deck of the Sulphur Bottom and sees Gatz defeated by Geetz. Mega Man is able to defeat Geetz, who, using his last forces, seriously damages Mega Man.