Lamune is an average fourth-grade boy with a passion for video games. After purchasing a cartridge from a traveling merchant girl and assisting her in selling the remaining stock, he takes it home to play "King Sccasher," eventually completing the game. The merchant girl then emerges from his television, identifying Lamune as the "Blood Relative of the Chosen Hero Lamuness" and requesting his aid. She is Princess Milk, and she transports him to the Hara-Hara World with the mission of reviving the Guardian Knights. To accomplish this, Lamuness must locate and unlock a shrine housing Tama-Q, a robot who becomes his Advisor Robot, and retrieve the key necessary to free the Knights. While the Guardian Knights are independent mechas, King Sccasher is piloted directly by Lamuness. His adversaries are Don Harumage and his subordinates, Da Cider and Lesuka.