Kimura plays the role of Ieji Hisashi who goes into a coma due to an accident but finds himself being unable to remember what happened in the last five years when he regains consciousness. With the 10 keys in his possession, he tries to find his lost past while struggling with the fact that he sees his current wife Megumi (Ueto) and son as people with masks on their faces as well as taking a keen interest in his ex-wife Nozawa Kaori (Mizuno) and finding out why he married and divorced her.
Upon his recovery, Hisashi is transferred to the 13th sales department where his new boss Kozukue Yukio will be played by Nishida Toshiyuki. Hisashi's neuro-surgeon Tsukuba Yoshiaki will be played by Oikawa Mitsuhiro. Tanaka Kei will play the coach of Hisashi's son Yoshio's soccer club while Higashi's colleagues Watanuki Shinji and Todoroki Haruki will be played by Suzuki Kosuke and Mitsuishi Ken. Watanabe Ikkei will play the director of Hisashi's company while Arai Hirofumi will play the ace of the first sales department who used to be rivals with Hisashi. 4-year-old Yoshio will be played by child actor Takahashi Rai while Hisashi's 13-year-old daughter Subaru will be played by Yamaguchi Mayu.