Season 1

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.

How did Mitsu and Azusa feel about seeing each other on the third Friday? Why were the two of them on the same bus that day? Sakiko and Jitsuo develop a strange sense of solidarity by sharing their feelings of in agony while the interview with the people involved is also futile and the truth is not clear.