Pharmacist Kiriko Urobuchi struggled between her specialization in traditional Chinese medicine and modern medical practices. One day, on her way home from the hospital, she encountered a mysterious girl. “Master Pharmacist of the Hidden World, I've come to fetch you.” Before she knew it, she found herself in a different realm where cell phones didn't work, overrun with people suffering from a mysterious infectious phenomenon. Was this a disease? Or a supernatural occurrence? Urobuchi Kiriko, along with the shrine maiden Mikagisui, sets out to investigate the mystery—!?