Watashitachi no Shiawase na Jikan

Watashitachi no Shiawase na Jikan (私たちの幸せな時間) is a manga series by Sumomo Yumeka. It was serialized in Comic Bunch.

Plot
They wanted to die for their own reasons.

Juri Mutou is the daughter of a once-famous pianist whose career came to an end after giving birth to her. After a traumatic event she experienced as a teenager, Juri has attempted suicide three times and has come to hate her mother. With her life clouded due to a dark past, her aunt Monica, a member of the clergy, invites her to visit a convict sentenced to death.

Yuu is a death row inmate charged with murdering three people, leading to many attempts at ending his own life within his jail cell. He frequently receives letters from Monica, who hopes to help him, but sees this as an act of pity. But when Yuu decides to meet Monica to say that he wants her to stop sending letters, he encounters Juri, a meeting that would change both of their lives.