Koibito Swap

A high school boy named Yuusuke Midorikawa has a girlfriend, Kayo Yoshioka, who was also his childhood friend. After confessing his feelings to her, they became an official couple, but she has recently grown distant. One day, Yuusuke sees Kayo leaving a karaoke venue with another boy, which upsets him. The next day, he meets Kotone Shiraki, a classmate who reveals herself as the girlfriend of the boy he saw with Kayo. The interactions between these characters lead to changes in their youthful relationships. The story is described as a bittersweet romantic comedy, with more sweetness than bitterness.