The protagonist, Sachiko Tachibana (played by Nozomi Sasaki), vows to take revenge on the monster Reina Hanai (played by Nagisa Shibuya), a monster as ruthless as a demon. When she was in high school, Sachiko was teased as a "murderer's daughter", and Rina became her only partner. However, behind Reina's angelic and gentle smile, there is the face of a murderous demon who kills easily. Rina charged Sachiko and her father with murder and took the life of Sachiko's father. 14 years later, Sachiko, whose appearance and past have all changed, once again confronts Reina, who has become a new mother. "Let her taste the taste of living hell", Sachiko enters Reina's family as a nanny. Can ordinary people who dedicate their lives to revenge drive monsters to destruction? The heroic revenge drama with repeated setbacks and entanglements began.