Kei is classmate of Misora since middle school and has known her from middle school upto currently in high school. They first meet on rooftop of their middle school due to Souma's arrangement and later Misora acknowledges Kei for his effort in saving someone using Misora's ability and completely trusts Kei and his decisions.

Kei is fast in deciding and has a swift thinking of solving problems. He joins the Service Club in their middle school and high school.

His ability enables him to retain and recall memories. He can recall and pinpoint even small details regarding the state of his senses.