For high schooler Kei—and for at least forty-six others—immortality comes as the nastiest surprise ever. Sadly for Kei, such a feat doesn't make him a superhero. In the eyes of both the general public and governments, he's a rare specimen who needs to be hunted down and handed over to scientists to be experimented on for life—a demi-human who must die a thousand deaths for the benefit of humanity.
12-year-old Oriko Seki, who lost her parents in a car accident, ended up living in her grandmother's Onsen Ryokan "Haru no Ya." With the ghost "Uribou" cohabitating with her and all the other odds, she ended up training to be a young female innkeeper. At first, she didn't like the training, but gradually felt her admiration for her title and began to train seriously. Thus, the growth of the young warrior Oriko begins.
The "Academy Island Incident" in which four "kings" cross paths... Since then, Silver Clansmen Kuroh Yatogami and Neko have been searching for their master, Shiro. Without finding any clues to Shiro's whereabouts, the two became disheartened. However, one day, they see HOMRA members Rikio Kamamoto and Anna Kushina being chased by someone.