The story follows the lives of two young people, Inuzuka Himari, who has yet to find her first love, and Natsume Yuu, a flower-loving boy, who remained best friends in their second year of high school, together in the gardening club. Sometimes Hiyori will tease him by say things like, "If Yu can't get married, I'll have to take the blame. It's hard when your brother calls him 'brother-in-law!" But when Yuu is reunited with his first crush from the past, the wheels of their relationship suddenly started to turn! Will Himari's newfound feelings help her break free from her "ideal friend" status?