We are brought back in time to when Yume and Mizuto were once a couple. A time when neither of them could control their nerves in what was their first ever relationship. Having already held hands and kissed before, the young couple are eager to take the next step. Spring break passes, however, with neither able to make the first move. Upon entering their third and final year of middle school, the two are regrettably put into separate classes. Alas, unable to spend as much time together as before, they both begin to grow apart.
Mizuto, this is Ayai Yume. 
She'll be your new sister.
.ميزوتو، هذه أياي يومي-سان
.ستكون أختك الجديدة
Mizuto, das ist Ayai Yume.
Sie wird deine neue Schwester sein.
Mizuto, esta es Yume Ayai.
Será tu nueva hermana.
Mizuto, esta es Yume Ayai.
Será tu nueva hermana.
Mizuto, je te présente Yume Ayai,
Mizuto, lei è Ayai Yume.
Da oggi sarà tua sorella.
Mizuto, esta é a Ayai Yume-san.
Ela será sua irmã.
Мидзуто, это Аяй Юмэ.
Твоя новая сестра.