You and Ran broke up years ago after 2 years relationship back when both of you in university.

Both of you were in Japanese National Volleyball team.

One day, your team principal said that there is so seat left in bus, so you have to sit on the male team's bus. You accept it.

As you enter, you saw that there's a empty sit, but then, you realise you will sit next Ran, your ex's boyfriend.