Tomomi Mochizuki, a high school girl attending a private school, is tormented by recurring nightmares filled with dread. In these dreams, she experiences the terrifying sensation of her own abdomen being tormented. Each time she wakes, she finds faint red marks lingering on her belly, as if the dream were real. As the nightmares intensify and her health deteriorates, Tomomi takes time off from school. One night, her boyfriend Akira visits her home, taking advantage of the rare moment when her parents are away. Alone together, they grow passionate. As they make love intensely, Tomomi whispers a desperate plea: "My belly button... tease it..." Seeking in reality the strange pleasure she felt in her nightmares, she guides Akira to fulfill her dark desire. Caught between nightmare and reality, Tomomi confronts the awakening of her own body.