The movie is based on the novel with the same title, written by Houjou Haruka, and the lead is played by Mizukawa Asami. It is about bilocation which is "when a person or an object is located (or appears to be located) in two distinct places at the same instant in time". It is similar to doppelgängers, however there are differences such as it's possible for the original person and the other self to interact with each other. Also, the other self would do the same actions/activities (synchronicity) as the original, somewhere close to the original (which is the starting point of this movie).
First, the movie summary. Takamura Shinobu (Mizukawa Asami) is arrested at a supermarket one day on suspicion of using a counterfeit bill. Apparently, 10 minutes ago, "she" had shown up using the same bill with the same number to buy something. The place the police had taken her though where people who had similar experiences and were troubled by their "other selves". "Bilocation" is what they call their other selves...
Senga's role is an university student whose life is in danger because of this bilocation, so he will be playing two roles.
Takada Sho will also be in this movie playing a mysterious boy who always covers his face with a neck warmer.