A girl who lives in the snow realm of the World tree.
Her long braids are her trademark.
Her name comes from the noun "ratio" and her work consists of helping animals who are troubled and of giving life to the forest.
She has a "milk tree" at home and she loves the milk that comes from it.
She is very skillfull: she cooks for her best friend Nemu and repairs Iroratio's stuffed animal.
She has been with Jamon ever since they were babies.

Ratio is a girl living in a ice world with his hairy friend Jammon, she will learn various things from the spirits and the people she encounters in every episode.