Initially skeptical of its supernatural properties, Emi discovers the mirror shows people their deepest regrets and can pull them into alternate realities. After her colleague Nakamura disappears into the mirror, Emi embraces her role as guardian and her family's gift of "the sight" – the ability to perceive boundaries between worlds. With help from temple caretaker Koji Matsuda and Ayane, a teenage girl who once escaped the mirror, Emi enters the mirror realm to confront its power. There she meets Hanako, her ancestor and the original guardian, who reveals the only way to end the mirror's hunger for souls is through a guardian's willing sacrifice.