The heroine, Miho Mamiya, goes on a three-night, four-day hot spring trip with her childhood friend and boyfriend, Kento Tanabe.

On their way to the ryokan, they are approached by a man traveling alone.

From the same hometown. Staying at the same ryokan. Such coincidences pile up, and he and Kento hit it off, becoming close.

——Only Miho doesn't know. That the two had met before. That a NTR (Netorase) plot has been arranged.

And that the hot spring trip has been orchestrated...