Mariko Tsuyuki is a supporting character in the Juon: The Grudge story. She is best known as the close friend of Rika Nishina, the social worker who becomes one of the central victims of the family curse. Mariko works as an elementary school teacher, a role that reflects a sense of responsibility and care for children. Her involvement in the narrative begins when she visits the Saeki house to investigate the prolonged absence of Toshio Saeki, a boy registered as her student who has never attended class. This act of concern leads her directly into the cursed home, where she encounters the hostile spirits. Rika, aware of the danger, rushes to save her but arrives too late. Mariko becomes another victim of the ju-on, her fate illustrating how the curse spreads through well-intentioned actions and ordinary social ties. Her personality is not explored in depth, but her profession and her decision to follow up on a missing student suggest a diligent and compassionate nature. She has no supernatural abilities and does not undergo any character development, as she appears only briefly before succumbing to the curse. Her primary relationship is with Rika, as the friendship between them is the reason she is drawn into the tragedy. Through Mariko, the story emphasizes that no one is safe from the curse, and even those who never set foot in the house can be doomed through their connection to someone already marked.