Mari is a supporting character introduced in the episode segment titled The Sandman’s Lair, which is part of the anthology series Junji Ito Maniac: Japanese Tales of the Macabre. She is depicted as a friend of Yuji, a young man who suffers from recurrent nightmares and is desperate to avoid sleep. Her background is not extensively detailed, but she is presented as an ordinary person, likely a student or a peer within Yuji’s social circle. In terms of personality, Mari is shown to be empathetic and reliable. When Yuji explains his tormented dreams and asks for her help to keep him awake, she agrees without hesitation, demonstrating a willingness to assist a friend in distress. Her motivations are rooted in concern for Yuji’s well‑being; she appears to genuinely want to alleviate his suffering and prevent him from experiencing the horrors that haunt his sleep. Within the story, Mari’s role is primarily that of a supportive companion. She interacts most closely with Yuji, as the plot revolves around their shared vigil against sleep. Her key relationship is therefore with Yuji, and their dynamic is one of trust and mutual reliance during a disturbing ordeal. Mari does not undergo significant development or transformation—the narrative focuses on the escalating supernatural threat rather than her personal growth. She remains a steady, grounded presence whose function is to provide Yuji with an anchor in reality as the fabric of that reality begins to warp. There are no notable supernatural abilities attributed to her; her strength lies in her ordinary, human capacity for care and vigilance.