Mizu ni Sumu Hana

A school field trip takes a tragic turn when the bus Rikka is on crashes and sinks into a lake, killing everyone aboard except her. Her survival is not due to chance, however. After being discharged from the hospital, Rikka becomes the target of a string of strange water-related attacks. These are carried out by a cruel aquatic figure who also calls herself Rikka. The second Rikka seeks something that the first possesses—something that may have been responsible for her survival. Questions remain about what this object is, who provided it, and the reason behind it.