Nameless Poison [aka Namonaki Doku] (2013)

Saburo Sugimura (Kotaro Koizumi) works for the PR department of a company which his father-in-law Yoshichika Imada runs. One day, Yoshichika Imada tasks Saburo Sugimura with work regarding a man named Nobuo Kajita. A complicated story unfolds from the request.