After her mother remarried, Kanami found herself with three new stepbrothers. They were all kind, making her feel warmth in her heart as if they had always been a family. But one of them was different. The youngest brother, Ken, began seeing Kanami not as a sister but as a woman, and started avoiding her by locking himself in his room. One afternoon, Ken finally pinned Kanami down. Yet at that moment, Kanami still didn't realize—this act was not an isolated incident, but the beginning of a chain of events that would drastically change her life forever.