Mayu no Uta

Summary

"I'll be your mother." After losing her biological mother, Mayu Kanda was abused by her guardian uncle every day, and could barely eat properly, but she just laughed it off. Until she met a mysterious beauty, Kamakura Komachi, who suddenly appeared. Is she, who acts like a mother, a ray of hope for Mayu? Or...? (Source: AniList; Ichijinsha, translated)