Ai no Hahaoya

The wife of [Dr. Fuji](https://anilist.co/character/130283/Dr-Fuji) and the mother of the late [Ai](https://anilist.co/character/146408/Ai).
When Dr. Fuji dedicated his life to resurrecting Ai, she decided she could no longer be his wife and left him, leaving behind her wedding ring.