Amatsu Mikaboshi was worshiped as the Japanese god of evil. Legend states that Mikaboshi acquired Kusanagi, the mystical Grasscutter Sword. The storm god Susanoo claims to have found the Grasscutter Sword within the body of the eight-headed dragon Yamato-no-Orichi; after it was gifted his sister Amaterasu, the magical sword served several heroes over time, finally resting for centuries in a heavily guarded temple for safe keeping before the Asgardian gods Thor, Fandral, Hogun and Volstagg freed it. The Asguardians failed to safeguard it, and it eventually ended up on Earth where the Hand sought it but were stopped by Black Axe, Sunfire, Daredevil and others while Mikaboshi claimed the sword.
Armed with the weapon, Mikaboshi Conquered Yomi (the underworld) and its demons, using these to destroy many of the kami and absorb their powers. The survivors fled from Ama or went into hiding (Hotei Osho, one of seven gods of happiness, took refuge in China as Ho Ti), and Mikaboshi sought to conquer the Olympian gods. He kidnapped Alexander Aaron, the son of the war god Ares, and influenced the son to to try to usurp his father's mantle as Olympian war god. During his raid of Olympia, Mikaboshi mortally wounded Zeus. Ares ultimately brought his son to his senses, and the messenger gods of two pantheons, Mercury (Olympian) and Inari (Japanese), tricked the Greeks and surviving Japanese into allying despite their pride; the combined efforts of the water deities Poseidon and Ame-No-Mi-Kumari flooded Mikaboshi's underworld, defeating him.
During the catastrophe known as the Secret Invasion of the extraterrestrial skrulls, the Olympian Hercules assembled a team of gods to defend the Earth. The team’s members were Mikaboshi, Snowbird, Ajak, Demogorge and Amadeus Cho they would later be named the God Squad. Together this squad of gods ventured to the Skrull planet of Satriani, where they confronted the the Skrull gods Kly'bn and Sl'gur't. In a swift skirmish Mikaboshi and Demogore were easily defeated by Sl'gur't, however Mikaboshi rose to his feet claming to be free of the Kami and seeking revenge, he managed to teleport to an unknown destination.