Sakurai Tomoharu is a single parent who has an extremely close relationship to his daughter. One of his hobbies is catching and collecting butterflies, and he has traveled to Taiwan to catch a very rare butterfly, the Troides magellanus. It's so rare it's been called the "phantom butterfly." The legend goes that whoever catches this butterfly will become a phantom themselves.

Back in Japan, Tomoharu's daughter, Ame, hasn't received a phone call from her father in days and begins to worry. However, when Tomoharu does return, he has no recollection of how he got back to Japan, or what happened at all. Ame notices strange things beginning to happen all around her ...

With the help of his neighbor Akiko, Tomoharu begins to piece together what happened back in Taiwan, and comes to a horrifying conclusion.