The main protagonist of Mugen Souls, Chou-Chou, plans to conquer the universe by subjugating the seven worlds it comprises, as she thinks the planets look pretty. Traveling from world to world with her trusty companion Altis, and loyal peon Ryuto, Chou-Chou aims to turn the heroes and demon lords of each world into her ‘peons’ (servants), saving the world from conflict in the process.

The protagonist is Syrma, a goddess aiming to stop an awakened ancient threat. Gameplay aspects include level caps of 9,999, large mecha, and billion-point damage.