Ooyama is just a timid high school boy trying to enjoy his peaceful, solitary life… or at least he was. Everything changed when the bold and mischievous Riko Akutsu from his class barged into his apartment one day—and never really left! Now, Ooyama’s bedroom has become Akutsu’s personal after-school lounge. She naps in his bed, devours his snacks, reads all his manga, and treats his room like her second home. No matter how much he protests, she refuses to leave—and Ooyama’s teenage mind can’t help but get flustered by her teasing behavior. But as the days go by, the playful annoyance between them slowly begins to shift into something warmer… and much harder to ignore.