High school girl Hatsu (Hori) lives with her brother Ling (Mamiya) and sister Akane and their parents. One day, she is caught by Ryoki Tachibana (Shimizu) who lives in the same apartment and is tossed around by Ryoki's unreasonable orders. At this time, her childhood sweetheart Azusa Odagiri (Itagaki) who moved away a few years ago comes back. Hatsu is naturally attracted to the way Azusa protects her as always. Even though Ryoki keeps trying to stop her, she still goes out with Azusa, but Azusa actually has a purpose unknown to others. At this time, Hatsu also knows Ling's secret...