The Angel of Charity.

Being naive and all, she never doubts when she's given an unreasonable request, and she would try everything she could to complete it. That's why her big sister, Sandalphon, is worried about her so much that she watches her with a drone over her head.

Her youngest-child personality always makes people around her worry, but when she has a syringe in her hand, she becomes a sadistic mad girl with a medical expertise.