Nagi is a diver from a quiet fishing village where a series of strange incidents have been occurring recently, including residents that have gone missing. One day, a stranger takes her to an office where she is asked to recover sunken treasure at Kaijin Reef. Nagi agrees to do so, but during her dive, she gets exposed to strange radiation. Afterwards, she starts to experience moments where she exponentially grows in size. This causes a lot of problems for her and the people surrounding her.