Kotori Itsuka is one of the main heroines in Date A Live series. She is Shidou's foster sister and a middle school student. Kotori is the head commander of Ratatoskyr which teaches Shidou about the spirit and spacequakes happening. She told Shidou how to save the spirits in a peaceful manner so as to prevent the spacequake from happening.
Kotori is actually a Fire Spirit. To be exact, she became a Spirit five years ago. The reason why Shidou regenerates his wound and comes back to life is because Shidou sealed Kotori's power inside him five years ago. It was around that time that there was a third entity which was said to be the cause of Kotori becoming a Spirit and the cause of Mana's, Kotori's and Shidou's memory to be erased.
Kotori's angel, Camael, contains the power of fire. Her weapon manifests itself as either a giant flaming axe or a heat cannon. Kotori also has a powerful regeneration ability, which Shido uses/borrows on many occasions when he is trying to make spirits fall for him. Basically, it is an ability that protects the user from certain death as long as the user has enough "mana." It also reverses all physical damage done on the person as if it never happened but only covers the recipient's body.
Kotori has two modes which is depicted by the ribbon she wears. The white ribbons depicts the Imouto Mode which makes her show love for her brother, which according to her, is that of her "weak self," a delicate little sister who is very dependent upon her big brother. The black ribbons depicts the Commander Mode which shows her tsundere sadistic bossy nature. While wearing them, she becomes her "strong self," a charismatic and sometimes cynical leader able to successfully command the airship, Fraxinus. According to Reine, the Kotori with white ribbons is the one that can honestly say how she feels, which would mean that the Kotori with black ribbons is simply putting a strong front because the situation requires so.
In her spirit form, Kotori acts the same as her ribbons' current color indicates. But if she stays in her spirit form for too long, her third, "Spirit personality," takes over and she becomes an aggressive and merciless killing machine, who only cares about battling enemies to death. It could be said that battling strong opponents (and utterly destroying them) is her only interest.The nature of Kotori's powers makes her prone to losing control over the urge of defeating another Spirit, and has caused widespread damage during the two times it was unleashed. For this reason, Kotori sees her Spirit powers as a last resort that she only chooses to use when desperate times come.
