Tadashi Kitayama appears in the "Morita Hospital" storyline within the Tomie narrative. He is Yukiko's boyfriend, frequently visiting her during her hospital stay for a kidney transplant. Tomie, using the alias Reiko Mizutani, manipulates Tadashi and Yukiko, telling Yukiko that Tadashi wants her dead and informing Tadashi that Yukiko confessed to an affair with a doctor, creating significant conflict between the couple. Tadashi has black hair and wears glasses. Upon first encountering Tomie at the coast, Tadashi experiences an immediate, intense "abnormal urge." He recognizes her resemblance to the murdered Tomie Kawakami from news reports and grows suspicious of her inconsistent background stories. After Tomie taunts him about expensive earrings and threatens to find a wealthier man, Tadashi stabs her to death. During police interrogation, he admits to an inexplicable compulsion to dismember her. Following Tomie's death, her kidney is transplanted into Yukiko due to a match. The transplant initially aids Yukiko's recovery, but Tomie's kidney later regenerates into a full human form inside Yukiko's body. Tadashi's actions directly facilitate Tomie's cellular propagation through this medical procedure. His narrative concludes with his arrest for murder, leaving his ultimate fate unresolved. His role illustrates Tomie's destructive influence through manipulation, violence, and unintended biological consequences.