Mari is a main character in Yohane the Parhelion: Sunshine in the Mirror. She is the daughter of a family of demon lords and resides alone in a castle on Warshimer Island. As a demon lord, she rarely shows herself to humans and initially appears cold and distant. In truth, she fears being hated by others because of her demon nature, and her isolation stems from this deep anxiety rather than genuine aloofness. Despite her withdrawn demeanor, Mari possesses considerable magical power, which she uses from a distance to protect the island. Her abilities manifest as ice‑based attacks, often sending streams of ephemeral fish and bubbles that can strike in a line. She is served by a highly skilled familiar named Pellapie. In the story, Yohane seeks out Mari to learn how to control her own magical singing powers, and Mari reluctantly becomes a mentor figure. Their relationship develops as Yohane helps Mari interact with the people of Numazu, gradually drawing her out of seclusion. Mari’s role in the series is that of a mysterious yet ultimately benevolent figure who bridges the gap between the human world and the supernatural elements of the setting. She undergoes gradual development as she learns to trust others and accept her place among the community.