On cold, still nights by the Nagata River outside Gifu, the air sometimes wrinkles like thin glass over the gravel banks. Once every 100 years, several small cracks open, and people and small things from the Ofim Empire, a medieval-magical realm, invade. They land in modern Japan. There's Sosuke and Sara; both begin alone near the Nagata River; all the other characters are in the city. The tone is a slice-of-life experience, with humor, kindness, paperwork, and a little bit of courage. Magic never replaces consent, study, or law; it enlightens, protects, and heals in thumb-sized ways.