In a futuristic world, Karin, a DNA manipulator, is sent back in time to prevent Junta Momonari from transforming into the infamous Mega-Playboy who fathers countless children, leading to a global overpopulation crisis. Surprisingly, Junta is not the womanizer he's destined to become; he's actually allergic to girls. However, a mistake in DNA alteration causes him to sporadically manifest the irresistible charms of the Mega-Playboy. Now, Karin must rectify her error before Junta's transformation becomes permanent, risking a future she's desperate to rewrite.