Mainu is a fast-paced action adventure set inside a mysterious 13-floor mall consumed by energy. When Tonu meets a girl named Venera, he learns that a powerful being named Ormatsu has unknowingly infused his excess magic into ordinary capsule toys—creating living creatures called Mainus. Drawn to the mall’s endless flow of light, food, and movement, Ormatsu spreads through the building like a black hole, splitting himself into thirteen extensions that drain the life of each floor. Tonu’s own force energy allows him to control the awakened Mainus and fight back. Guided by Venera, he must collect, master, and unleash their power to stop Ormatsu before the entire mall—and reality itself—is consumed.