When Toshinori, a quirkless kindergartner meets a young girl, it's under not so strange circumstances, where she saves him from the lack of mercy at the hands a bully named Noboru. He learns her name is Hisoka, and they make a promise to one another, and a reason to see each other again.

When Toshinori's wife is taken away for a crime she did not commit, he's left alone to raise their five year old son Masaki. But ten years later, when she returns out of the blue.. her son hates her. She must regain his love, while dealing with the fact that she had been wrongly imprisoned for ten entire years, among other things..