To save his great-granddaughter, he must relive a story he has buried for a lifetime.

When elderly Thomas Haruki sees small horns sprouting from eight-year-old Alice's head, he recognizes a terror he has spent a lifetime trying to forget. He believes it is the mark of the Oni, a demon curse that has haunted his family across generations. With his memory failing, he begins to tell her a secret story, a desperate, final attempt to prune the horns and protect her from her fate.

It is a story that begins not with the bombs of Pearl Harbour, but with the screech of giant mythological birds tearing the sky apart. As a young boy, Tomoe is plunged into a hidden world of Japanese folklore, escaping the destruction through a magical portal with a mysterious girl named Jane. His journey takes him from the bottom of the ocean to a castle made of sand, and finally to the breathtakingly beautiful, and terrifyingly restrictive, Crystal City.

In this shimmering prison, to be different is to be dangerous, and to remember one's heritage is to risk being branded a monster. But Tomoe's story is more than a fantastical memory; it is a confession. The same darkness that hunted him then now threatens his family. The horns on Alice's head are proof that the past is never truly past. To save her, Thomas must finally confront the truth he has spent a lifetime running from: that the only way to defeat a monster is to embrace the horns you were born with.