Hinata has been in love with his best friend, Makoto, for years, but his heart is broken when Makoto moves in with his girlfriend. In the wake of this emotional devastation, Makotos younger brother, Rou, suddenly decides to move in with Hinata.

To Hinata, Rou has always been like a spoiled and cheeky little brother, someone cute he could never see as a romantic prospect. Unbeknownst to Hinata, however, Rou has secretly harbored a crush on him for a very long time. Now that Rou is grown up, he approaches Hinata with a new, manly face and begins to aggressively yet sweetly pursue him, begging Hinata to finally see him as an adult and a potential partner.

The story follows Hinata and Rou as they navigate the shifting boundaries between a childhood friendship and an adult romance. Caught off guard by Rous persistent advances, Hinata finds himself constantly at the mercy of Rous mean-but-sweet behavior and occasional clumsy kindness. The central conflict revolves around their struggle to reconcile how they see themselves with how they want to be seen by the other. For Rou, this means being recognized as a serious love interest rather than just a kid brother. For Hinata, it involves confronting his long-held, one-sided feelings for Makoto and reevaluating his perception of Rou as he is now.

The narrative explores what it means to be grown up, starting from a place of unrequited love and evolving into a relationship between two people trying to bridge the gap between their past and their future.