Kazuki is Yuujis older sister who taught him during his early years and served as the main financial provider for the family. Unlike most families, she played a central role in supporting the household instead of her father. Despite being small in stature, she possesses a sharp intellect and exceptional quick thinking skills, earning her the label of a genius. She is the same age as Amane, both of whom attended Takizono Private School and were part of its basketball team.
In Grisaia no Rakuen, she survived the accident and Ichigaya retrieved her body and used her brain to run a super computer with the name "Thanatos." U
In Grisaia no Rakuen, she survived the accident and Ichigaya retrieved her body and used her brain to run a super computer with the name "Thanatos." Unable to use her body—only her brain—she helps train the five girls to help Yuuji who is being held captive by his own organization. Kazami Kazuki uses a mechanical hand afterwards.
An unspecified time ago, she died in a bus accident. In the present, the memory of her death greatly affects Amanes and Yuujis lives.
In the end of Grisaia Rakuen, Kazami Kazuki reveals that the prosthetic hand that is used by her is just a fake.