Tomie Hashimoto is a dreamy teen who writes homoerotic horror fiction in which she imagines herself as Ann Bathory, a vampire. Introspective and lonely, she is picked on and bullied by her classmates at school, and lives alone with her loving, yet distant widower father, Kazuhiko Hashimoto.
One day, while admiring an ornate jewel-encrusted cross necklace in an antiquities shop, Tomie H. meets a strange, beautiful girl with a mole under her left eye. The mysterious stranger says her name is Tomie Kawakami. The two girls quickly become best friends, with undertones that hint at something deeper than friendship. Tomie H. dedicates the character of Mary from her fanfiction to her new friend, but it soon becomes clear that their meeting was not purely accidental; Tomie K. has an agenda, and it revolves around Tomie H.’s father.
It is revealed that Kazuhiko was involved in a relationship with Tomie K. many years ago, a connection that ended in Tomie K.’s murder. Yet Kazuhiko remained obsessed with Tomie K., to the point that he even named his own daughter after her. Tomie K. returns to terrorize the family and tries to persuade Kazuhiko to murder his daughter. The tension culminates in a brutal act: Kazuhiko murders and decapitates Tomie Kawakami, hurling her head into a nearby river. Tomie H. discovers the talking head and nurses Tomie Kawakami back to health as she regenerates. She famously spends long hours cooking and caring for her, but after a fierce argument, Tomie Kawakami is tossed off a building by Tomie H.
Moments later, Tomie Kawakami reappears on Tomie H.’s front porch, and Tomie H. shoots her with an arrow, killing her. She and her father then attempt to freeze Tomie Kawakami into a block of ice to halt regeneration, but Kazuhiko releases the frozen head after hearing her pleas. Tomie Kawakami attacks Tomie H., and a head injury prompts Kazuhiko to lock his daughter in a freezer room. Tomie Kawakami laughs as she and Kazuhiko walk away, hands clasped together. The next morning, a worker from the ice-sculpture company finds Tomie H. and saves her life.
Tomie H. is now shown living alone, with her father missing, though she remains grateful, believing he weakened the cold in the room to spare her from Tomie Kawakami. She returns to her room and continues writing, finishing with a haunting line.
> Ann and Mary are friends again; there will be no issues this time. Ann will raise her to be a real friend, a friend whom she can depend on.
Finally, Tomie H. opens her desk drawer and confronts a dismembered, regenerating ear of Tomie Kawakami, a chilling reminder that the danger may not be over.
