In sixth grade, childhood friends Yukiya Asagi and Miku Sakura created a game with the objective to embarrass the other person by taking turns saying "I love you." Four years later, even as they are entering high school, the two are still trying to one-up the other and claim victory. However, as tender feelings begin to bloom in their hearts, the simple phrase has taken on new meaning beyond the rules of their game.

With the passing of each day, the urge to become more than childhood friends grows—but both Yukiya and Miku resist making the first move, hesitant about what is in store once the game finally ends.