Kaiya is the daughter of Doriyaku Fuyutama and an yet to unnamed mother, who died shortly after her birth. Doriyaku suffered a great deal from the loss of his love and was unable to look at his child with you seeing a spitting image of his wife. Knowing that the young man would never be able to love and care for Kaiya properly Kaijin Fuyutama, Kaiya's godfather, took on the responsibility of being the father to the young girl. Doriyaku, convinced this choice would be better for his daughter, stepped aside and became more of an uncle figure uncle.
Together they thought her the power of Shadow and Kitoujutsu. By the age of 5 she was already jumping through shadows and preforming some of the more complex Kitoujutsu that took Doriyaku ages to learn. Despite this Doriyaku was absent for a majority of Kaiya's life, which was most evident when she was about six and half. It was at this time that he disappeared for five years. Shortly after him leaving, the Fuyutama Clan decided that it would be best to inform Kaiya of who her father really was and how her mother died. Because of this the young kunoichi would come to harbor a small amount of hatred for her father, who wasn't their for her.
She later became a member of the international SENSHI, where she has gained the level of First Class Third Tsurugi (一級三代目剣, Ikkyū Sandaime Tsurugi) within the Kōsen-butai (交戦部隊 "Combat Unit").
Kaiya wears a simple outfit that consent as of a black tank top with buckle straps, along with forearm length gloves with buckles near the top. Black shorts, with a black skirt over it, with a weapon pack on her leg. A special Fuyutama blade crosses over her butt. Boots that are near mirror images of her gloves cover her feet.
Kaiya is a private person who will only really speak to her friends. She can become very protective of the people she cares for. She is fast on her feet and quick minded. Her brilliance is what earned her the name Bourei no Kousai (光彩亡霊 "Brilliance of Spirits"). The clan feels that she is the brightest mind to come out of the clan yet. This skill all so makes her a deadly member of any team she is a part of.