Ruka remarried and has a new family. She is in love with her husband, but she is unable to grasp the right distance from her stepson, and their relationship has been strained. Then her husband decides to go on a company trip. It's the first time they'll be alone together. Ruka takes this opportunity to try and get closer to her son, and actively tries to get intimate with him, but... Ruka's voluptuous, mature body and defenseless behavior ignite her stepson's desire.