Tragedy strikes as schoolgirl Emili is abducted and murdered by a stranger. Four friends - Sae, Maki, Akiko and Yuka - are present at the scene of the crime, but none of them can remember his face, and the crime goes unsolved. Fifteen years later, the adult Sae has grown extremely wary of men, forever scarred by Emili's faceless abductor. When a timid suitor vows to protect her from the outside world and proposes marriage, she decides to accept.

Maki is now a teacher at a rigorous elementary school, and engages in self-defense training in an attempt to overcome her sense of helplessness. When an attack occurs at Maki’s school, it brings back vivid memories of the heinous crime she witnessed 15 years earlier. This time, Maki takes action to confront the perpetrator, resulting in unforeseen consequences...

Insecure by nature and harboring an inferiority complex, Akiko has withdrawn from society and lives a reclusive life at home. But things change when her brother Koji, his wife and her daughter Wakaba suddenly move back home from Tokyo. Akiko begins to bond with her young niece Wakaba, but then begins to notice signs of a strange relationship between the girl and Akiko's brother Koji...

Yuka's mother always favored her sickly older sister Mayu. Now grown up and an owner of a successful flower shop, Yuka still feels unjustly ignored. When she learns that Mayu has recently married Keita, a gentle policeman, Yuka's jealousy inspires a plan to seduce him. As her plan encounters complications, she receives an unexpected letter from Asako...

It’s been fifteen years since Asako’s young daughter Emili was abducted and killed by a stranger. With the case still unsolved, Asako struggles through life with no outlet for her resentment and despair. One day, Asako receives a new piece of information from Yuka, one of the girls that witnessed the crime fifteen years ago. Armed with this vital new clue, Asako begins to close in on the truth once and for all as PENANCE spirals to a stunning conclusion...