Fukase Kazuhisa, a salaryman with an unremarkable life, finds a hobby in drinking coffee, which leads him to meet his girlfriend, Mihoko Ochi. One day, Mihoko receives an anonymous letter accusing Fukase of being a murderer. This triggers Fukase's memories of a traumatic incident from 10 years ago, when his friend Hirosawa Yuki died in a snowboarding accident with classmates Tanihara Yasuo, Asami Kosuke, Murai Takaaki, and Murai's sister Asuka. A secret
