Erin-chan is the young 10 year old daughter of Soyon-san. She is an outsider in a village that takes care of the Grand Duke's military might, the toudas. Her mother, Soyon-san, is an outsider vet brought in to take care of the toudas. Erin-chan encounters many problems and learns many new things while aspiring to become a vet, like her mother, who cares for the all important toudas.