Sunset.

Hasebe Kaori is a rookie movie director. She consults with new screenwriter Kai Chihiro about her movie's screenplay. The script is based on the Sasazukacho Family Murder Case that occurred 15 years ago. That murder case involved a hikikomori man who murdered his younger sister at their home and then set their home on fire. The fire also killed his parents. The town where the murder took place is also the hometown of Kai Chihiro. Both Hasebe Kaori and Kai Chihiro have secrets related to the family murder case. While Hasebe Kaori and Kai Chihiro look into this murder case for their movie, a shocking truth is uncovered.