Kotori Itsuka

Shido's 14-year-old stepsister with red hair and ruby eyes. She is a cute girl characterized by her twin tails, but she also serves as the commander of , aiming to eradicate spatial disasters through negotiations with spirits, with Shido as the mediator. Although Shido and she are not related by blood, they have recognized each other as family through shared hardships since childhood and are now bound by a trust greater than that of blood relations. She is fond of horoscope and blood type fortune-telling.

When wearing a white ribbon, she is in her cheerful and innocent "sister mode," but when she switches to a black ribbon, her personality drastically changes to "commander mode." In "commander mode," she becomes sarcastic and cool, forcing Shido to learn about male-female relationships and mercilessly exposing his embarrassing past and failures if the desired results are not achieved. However, this is just a switch between public and private roles through self-suggestion, and her personality itself does not change; her affection for Shido remains constant in both modes. To differentiate between her roles, she calls him "Onii-chan" in "sister mode" and "Shido" in "commander mode," though she might revert to "Onii-chan" when extremely flustered even in "commander mode."

While Shido negotiates (dates) with spirits, she monitors him from the command center of , giving instructions via intercom, though sometimes her misguided orders endanger him. She loves Chupa Chups and always has one during missions.

Her subordinates' trust and loyalty are extremely strong; even after discovering Kotori is a spirit, they unite and take action to save her from her destructive impulses. Kotori herself regards the members of her unit as family or children, knowing all their faces, names, affiliations, and ranks, even those she has never met.

Her identifier is . Her spirit gear is a kimono with wide sleeves and a hem, reminiscent of a demon with two pure white horns, called . Her manifested angel is the flaming battle axe , which can switch to a form called [Cannon (Megiddo)] that emits high-temperature rays when the staff part is attached to the arm. She can regenerate any injury with the power of flames, using them as a barrier to block attacks, and has extremely high offensive, defensive, and regenerative capabilities. However, the more she uses her spiritual power, the stronger her destructive impulses become, eventually risking the collapse of her human ego. Unlike other spirits, she can control her spiritual power to some extent by managing her mental state, allowing her to cause spatial quakes at will.

As mentioned, she is the first to have her spiritual power sealed, but she is counted as the "Fourth Spirit" in terms of appearance order among the spirits.