A sudden accident shatters the everyday happiness two couples had always taken for granted — and exposes a secret one of them kept hidden for years.

Itsuki reveals he saw Azusa and Mitsuru together on "the third Friday." Sakiko wants to believe her husband, but begins investigating their secret.

As their investigation stalls, Sakiko and Itsuki bond over shared frustration. A call from the police leads them to retrace Mitsuru and Azusa's steps.

The discovery of two sets of tickets forces Sakiko and Itsuki to confront the possibility of an affair. Sakiko then finds a new clue on Mitsuru's phone.

Sakiko follows Mitsuru's trail all the way to Nagano, while an unexpected guest from Azusa's childhood pays Itsuki a visit.

A sudden return brings Sakiko, Itsuki and a familiar face together for the first time. As truths emerge, Sakiko reflects on her life with Mitsuru.

A familiar face challenges Sakiko and Itsuki to define their relationship, as the truth about Mitsuru and Azusa's third Friday meetings unravels.

Sakiko doesn't return after learning the truth. Worried, Mitsuru gathers her friends at a café, hoping to learn more about the side of her he never knew.

Sakiko enjoys time with a man and his children by the sea, while a troubled Mitsuru learns his wife was a very different person before they met.

Sakiko, Mitsuru and Jitsuo reveal their past and secret, and have a completely different relationship from before. Each of us chooses our lives...