Seijo Dakedo Yami Ochi Shitara Hiyoko ni Narimashita! @Comic

After betrayal and death, the strongest saint in the human world is summoned to the demon realm and reborn as a tiny yellow chick. She resolves to repay the demon lord responsible for her fluffy new form, but her reckless errands leave chick-shaped holes in doors, while her innocent training overwhelms the demon knights. Her baby-like mind makes life as a familiar a string of mishaps. The supposedly merciless demon lord instead blushes and decides to raise her as his daughter, charmed by her courage and cuteness. As he dotes on her and protects her, the runaway chick girl’s antics keep winning over those around her.