Tsukumo Murasame is a Zweilt Guardian of the Giou Clan, specializing in defensive combat alongside his partner and older sister, Toko Murasame. He possesses the "Ears of God" (Kami no Mimi), granting him abilities like sensing presences, hearing thoughts and emotions, telepathic communication, and speaking with animals, especially birds. His weapon, manifested via a ring, is the gun Knell (Funeral Bell), designed to exorcise Duras demons from possessed humans without harming the host. Knell's appearance shifts to black when Tsukumo activates "Neru Pia Blanca," significantly boosting its power to separate Duras from their human vessels. Physically, Tsukumo has short silver-white hair, golden Zweilt eyes, and a slim, athletic build. He typically wears a gray school uniform with a first-year high school purple necktie. His personality balances calmness and approachability; he avoids conflict but engages in mild teasing. He often carries snacks, sharing them generously as gestures of friendship. Though reserved, he demonstrates deep concern for allies, especially Toko and Yuki Giou. His empathic abilities sometimes overwhelm him, causing distress when exposed to others' pain. Tsukumo and Toko share an exceptionally close sibling bond, often mistaken for a couple due to their physical closeness and mutual devotion. They coordinate seamlessly in battle, with Toko handling close combat and Tsukumo providing long-range support. He prioritizes her safety and expresses sadness over never having married her in a past life. Their partnership extends to protecting Yuki Giou, whom Tsukumo considers a cousin and close friend. He readily risks severe injury to shield Yuki during conflicts, reflecting his fierce loyalty. Tsukumo belongs to one of the Ten Divine Houses. At age seven, he and Toko trained in Kyoto under Shizuka Usui. He keeps rabbits and celebrates his birthday on October 10. While his past lives are minimally detailed, he recalls having a girlfriend in one incarnation. Throughout the series, Tsukumo's relationships evolve beyond his sister; he offers support to the emotionally withdrawn Shusei Usui, eventually bridging their distance by sharing food and fostering camaraderie among the guardians.