Watashi no Okaasan The Alien Who Saved Me from My Mother's Abuse Becomes My True Mother.

Synopsis

Towa is an elementary school child abused by her mother. She learns the being who saved her is an alien who has taken over the mother's body. Towa manages to feel familial love from the alien who, though clumsy, tries to become her "mother." (Source: Kadokawa, translated)