Makoto Teruhashi serves as Kokomi Teruhashi's older brother, recognized by his distinct blue hair and blue eyes. He stands 178 cm tall, weighs 64 kg, and was born on March 4th (Pisces) with blood type A. Publicly, he is known as the popular idol and actor Tōru Mugami, an identity central to his entertainment career. His defining characteristic is an intense obsession with his younger sister Kokomi, driving extreme possessiveness and a compulsion to control her relationships. He openly declares himself the only person worthy of marrying her, aggressively confronting perceived romantic rivals. He directly threatens Kusuo Saiki with statements like, "Stay away from my sister, you four-eyed freak" and "I'm the only one who can touch her precious body!" This fixation creates significant strain, leaving Kokomi visibly frightened and uncomfortable around him. After discovering her interest in Saiki, Makoto visits the Saiki household to insult Kusuo and assert his self-proclaimed right to Kokomi, provoking her to yell, "I hate you!" – a reaction that deeply upsets him. Makoto's actions consistently undermine Kokomi's autonomy. For instance, when accompanying Makoto (in his Tōru Mugami persona) to a movie theater where she encounters Kusuo, Makoto unexpectedly back-hugs her, causing distress. He later blames Kusuo for the resulting awkward situation, escalating her discomfort. His behavior positions him as a disruptive force in Kokomi's life, marked by her fear and resentment, highlighting their fractured dynamic.