Kou Minamoto is a middle school student at Kamome Academy and a member of the famed Minamoto Clan of exorcists. He is the younger brother of Teru Minamoto and the older brother of Tiara Minamoto, born into a lineage renowned for combating supernatural entities, including the legendary defeat of Shuten-doji by an ancestor. Kou initially idolizes Teru and strives to become a skilled exorcist like him. However, his family's rigid belief that all supernaturals are inherently evil becomes a source of internal conflict as his story unfolds. Physically, Kou is a teenager with spiky blond hair, light blue eyes, and noticeable canine teeth. He wears Kamome Academy's middle school uniform, typically featuring an unbuttoned teal jacket over a black shirt, a loosely worn cream-and-brown striped tie, and a red sweatband on his right wrist. A distinctive trait is the red traffic-safety amulet (omamori) worn as a piercing on his right ear, earning him nicknames like "Traffic-Safety-Earring Boy" from peers such as Mitsuba. He carries the Raiteijou, a spirit staff disguised as a black umbrella, though its full power remains sealed after an early encounter with Hanako. Kou exhibits a cheerful, impulsive, and justice-driven personality. He often acts rashly without forethought, leading to mistakes, but consistently demonstrates kindness and open-mindedness. Despite initially aiming to exorcise Hanako, Kou revises his stance upon recognizing that not all supernaturals are malicious, defying his family's teachings. This moral flexibility becomes central to his character as he prioritizes understanding over blind exorcism. He struggles with deep-seated insecurities, feeling overshadowed by Teru's competence and reduced to domestic responsibilities like cooking, cleaning, and caring for Tiara. These insecurities fuel a self-sacrificial tendency; he repeatedly risks his life for others while undervaluing his own worth, believing no one depends on him. His abilities derive from his exorcist heritage. He naturally sees and interacts with supernaturals without summoning rituals. Using the Raiteijou, he channels spiritual energy into lightning, though his inexperience often causes self-electrocution and accidental injuries. His spiritual power is initially underdeveloped compared to Teru's, but he gradually hones his skills through conflicts. Kou also exhibits partial memory retention in altered timelines, experiencing dreams and subconscious actions tied to his original self's experiences. Key relationships define his development. His bond with Teru is marked by admiration and tension, escalating when Kou protects Hanako from Teru's exorcism, leading Teru to delegate Hanako's fate to Kou. With Nene Yashiro, Kou forms a protective friendship, initially harboring a crush fueled by her "cute smile" (his stated romantic preference) but later settling into a platonic, supportive dynamic. His most complex relationship is with Mitsuba Sousuke, a classmate killed in a car accident. After encountering Mitsuba's ghost, Kou blames himself for not befriending him while alive and becomes determined to grant his wishes. This culminates in a near-suicidal attempt to join Mitsuba in death after Tsukasa corrupts him. Grief over Mitsuba's destruction drives Kou to vow strength against evil supernaturals. In the "New Present" timeline created by the Clock Keepers' interference, Kou's existence is altered. Unaware of Nene, he forms a close friendship with Mitsuba, who is alive in this reality. This version displays greater supernatural knowledge and persistence in forging bonds, contrasting his original self's obligations. After regaining fragmented memories of the original timeline, he collaborates with Mitsuba to rescue Nene from the Red House. Tragically, he is possessed by Tsukasa during this mission and later transformed into a supernatural by the Red House. Forced to lure Nene to her doom, he rationalizes this as making her "understand" the House's nature. He is ultimately exorcised by Teru while attempting to free Nene, accepting his fate with the reassurance that they will reunite in the "Old World". Kou's character arc emphasizes maturation through adversity. Early recklessness evolves into measured courage, notably during the Red House arc, where he confronts grief by meeting Mitsuba's mother and his own deceased mother, learning that death abandons the living. This hardens his resolve against self-sacrifice. He faces repeated failures—such as inadvertently triggering Amane's murder of Tsukasa or enabling the Broadcasting Club's barrier destruction—but persists in protecting others. His journey consistently challenges his self-worth, culminating in acknowledgments that others value him, though his foundational drive remains ensuring the happiness of those he cherishes.