Rintarou Amano has resigned himself to the fact that he is going to have to take care of his incompetent childhood friend Maki Nakatsugawa for the rest of their lives, especially now that they are university students sharing a roof. But when they start living together, Maki, who was innocent and pure until now, starts depending on Rintarou to appease his carnal urges. With the freshly minted pervert finding the very sight of Rintarou a turn on, Rintarou must decide whether he should draw a line or explore his feelings for his friend. [Written by MAL Rewrite]