A Japanese middle school girl born and raised in Japan.

Though her mother is of Irish descent and she looks unmistakably Western, Erin is, in every way, an ordinary Japanese girl. (And no, she can't speak English.)

She lived a perfectly normal life until entering middle school, when a chance encounter with Riria and Anna led her to discover that she was a user of ancient mythic magic long thought lost.

Since then, Erin has begun a secret life as a magician alongside Anna and Riria, finding herself in the middle of various incidents involving magicians across Tokyo.