Ruruho

A young girl who adores Calt, and calls him "Onii-chan." She's been living alone in Rat village, waiting for Calt to return. Even though they're not blood-related, she trusts Calt more than anyone else in the world.

One fateful day, Ruruho had gone to a church's mass with her parents while on holiday. There was a sudden earthquake, and her life was saved by a priest, but her parents both died and suddenly Ruruho was alone. Since Calt's father had also died at that time, she'd come to live with him.