On is in his third year of high school. His friends Tsubasa, Masami, Jun and him have always gotten along and the four of them have spent most of their youth in fun together.

On planned to continue his studies in a Tokyo university and though all four of them had chosen to do different things after graduating, he believed that their relationship would still remain the same. However, on the night before their graduation ceremony, when he sneaked into their school with Tsubasa, he was suddenly kissed by the latter!?
僕たちの青春はずっと続くと思っていた　高3の温（おん）は、つばさ達4人の仲間で楽しい高校生活を送っていた。卒業後、温は東京の大学に進学することに。進路はそれぞれだけど、みんなとの関係はこのまま変わらないと思っていた。卒業式前夜。つばさと2人で学校へ忍び込んだ温は、突然、つばさにキスをされ…!?