Childhood friends Chiaki and Kazuma have been brought up like brothers, but the illusion of family shatters when Kazuma catches Chiaki touching himself, and in the heat of the moment, ends up lending a hand.

From that night on, the two of them help each other satisfy their base urges—that is, until Kazuma gets a girlfriend and Chiaki realizes his feelings go beyond friends with benefits. Will these childhood friends be able to go back to the way they were before? Or will their relationship manage to bloom into something more?