Tenshi no Naifu(2015)

Tenshi no Naifu is a Japanese drama following Takashi Hiyama, a cafe manager raising his young daughter alone after his wife Shoko was killed by three teenage boys four years earlier. Protected by juvenile law, the killers escaped prosecution while Takashi and his family endured relentless media scrutiny. Now, despite warnings from his friend Kana and employee Yudai, Takashi secretly searches for the three boys. When someone begins targeting them for murder, detectives focus on Takashi—who once publicly vowed revenge. As bodies pile up, Takashi races to uncover the truth behind the killings while fighting suspicion that he's the vigilante killer. The series explores grief, justice, and the cost of vengeance in a system that failed one grieving father.