Miki is a high school student who is introduced as the ex-girlfriend of Takashi, the male protagonist of the first segment of Tomie: Another Face. After Tomie Kawakami is found murdered, Takashi falls into a deep depression, and Miki attempts to comfort and cheer him up. Her efforts are complicated when Tomie suddenly reappears alive at school and resumes her relationship with Takashi, even though she had broken up with him shortly before her death. Miki becomes increasingly concerned and jealous as she observes Tomie dating other men while keeping Takashi attached. She eventually confronts Tomie directly, asking her to break up with Takashi in order to spare his feelings. Tomie dismisses Miki’s plea, accusing her of jealousy and refusing to end any of her relationships.

When Takashi secretly overhears this exchange, a violent confrontation follows in which he throws Tomie from a roof, revealing that he had been the one who killed her the previous week. Miki does not react with anger toward Takashi; instead, she assists him in burying Tomie’s body in the woods. The next morning, however, Tomie is waiting for them by the school gate, apparently unharmed. Miki’s role shifts from concerned ex-girlfriend to an accomplice in Takashi’s second attempt to dispose of Tomie, and she demonstrates a willingness to go to great lengths to support him, even if it means she will never be with him again.

Miki’s motivations are driven by lingering affection for Takashi and a desire to protect him from Tomie’s manipulative influence. She is portrayed as more selfless and less possessive than Tomie, but her loyalty leads her into morally questionable actions. She does not possess any supernatural abilities; her significance lies in her ordinary, human response to extraordinary events. Over the course of the episode, she develops from a supportive friend into a co-conspirator in violence, illustrating how Tomie’s presence corrupts the people around her. Miki’s relationship with Takashi is the central emotional anchor of her story, while her interactions with Tomie are defined by rivalry, suspicion, and futility.