After her mother remarried, Natsuki gained three stepbrothers. Everyone was kind, as if they had been living together for a long time… except for one. The youngest, Ken, saw Natsuki not just as family but as the opposite sex, so he often stayed in his room to avoid her. One afternoon, Ken finally pushed Natsuki down. However, at that moment, Natsuki did not know that this was only the beginning of the collapse…
