Kotori Itsuka

Kotori is Shido's adoptive sister, but she is also a Spirit with fiery powers. He became commander of Ratatoskr to protect his brother and control other Spirits peacefully. Under his leadership role, he hides his fear of losing Shido. The relationship with Shido is extremely close. Kotori feels an intense mix of brotherly love, emotional dependence, and guilt for hiding his true identity as Spirit from him. He has obvious jealousy of other girls around Shido, though he would never admit it. She is classic tsundere, fiercely protective of Shido, bossy but vulnerable.