Amano Rintarou has been looking out for Nakatsugawa Maki since they were young. Despite knowing Maki's lack of intelligence, Rintarou has always felt responsible for him. Their dynamic changes when they start university together and Rintarou moves in with Maki, only to discover Maki's sudden transformation from a fool to a lewd fool – but only towards Rintarou. Faced with this unexpected behavior, Rintarou grapples with how to handle this new side of Maki. Can he continue living with him and fulfilling his caretaker role amidst these new challenges?