Yousuke arrives in the bustling tourist city of Kazashiro to attend school there, charmed by its Western-style streets and the exotic atmosphere they create. His boarding house, Oasis, is run by his aunt Yuuko — and a witch named Ayari is living there too. He soon meets two more witches, Suzuno and Misumi, and reunites with his older-sister-like childhood friend Ririko, who turns out to be a knight. Every day brings something new, and before long, all of them are pulled together into another world entirely.