Description: This spring, the main character entered Seiyo Gakuen, a local preparatory school. He had a secret that he couldn't tell openly. "To all the new students who attended the entrance ceremony on this fine day. Congratulations on your admission. On behalf of all current students, I would like to extend a hearty welcome.'' Student council president Hotaru Konoshita smiled on stage. The main character's sister-in-law, who became a family member through their parents' remarriage. The turning point in their unsettled relationship is when their parents suddenly decide to go on a business trip overseas. A secret and unhealthy cohabitation life is about to start!