In 1907 Japan, nineteen-year-old Shinohara Sayo inherits an ancient family rite that transforms her into a bloodthirsty supernatural being.

The names of her supposed ancestors appear beneath her skin, granting her the power to save those she loves from otherwise certain death.

But one name belongs to Kawase Fumi, a woman who helped raise her and mysteriously disappeared years ago.

As Sayo searches for answers, the legacy she once revered begins to unravel, revealing a horrifying secret buried beneath generations of family devotion.