In sixth grade, childhood friends Yukiya Asagi and Miku Sakura invented a simple game. The rules were straightforward: take turns saying I love you to each other, and the first person to get embarrassed loses. What began as a childish dare has continued for four years, now following them into high school where the two stubbornly keep trying to outdo one another in their ongoing battle of wills.

The game has become a comfortable routine, but the feelings behind the words have shifted. Both Yukiya and Miku have secretly developed genuine romantic feelings for each other, yet neither is willing to admit it. Yukiya wants to win the game so he can finally confess his true feelings, while Miku aims to win in order to force him to admit he likes her. The very phrase that once served as a playful taunt now carries real weight, and the old game has become a shield. As long as they are playing, saying I love you is just part of the competition, a safe way to express something neither is ready to fully acknowledge.

The setting is their everyday life at school and in the spaces where their long friendship unfolds. Yukiya, whose voice is provided by Kaito Ishikawa, is determined to break free from his past image and use a more confident approach to finally fluster Miku. Miku, voiced by Miku Itō, is equally fond of teasing him and keeping the upper hand. As they continue to exchange these loaded phrases, each tries to maintain a composed exterior while their hearts race beneath the surface. The central tension lies in their mutual fear of what will happen once the game finally ends, leaving them hesitant to make the first real move beyond its rules.