Taro Sakamoto was once one of the most feared assassins in the criminal underworld, until the day he fell in love, left that life behind, and started a family. Now the owner of a small convenience store, he lives a peaceful existence despite looking nothing like the legendary killer he once was. But his past eventually catches up with him when former enemies, colleagues, and criminal organizations reappear. To protect his wife, daughter, and new friends, Sakamoto must fight again while keeping his promise never to kill, relying on his experience, instincts, and abilities that remain far beyond ordinary.