His life seems to revolve around music - he tells Kahoko that he sleeps, wakes up, plays the cello, then repeats the process, other than eating, going to concerts with his family and visiting the library to learn more about music.
He is currently living at his aunt's house. He enjoys reading as well as studying the history of music and structures of instruments. In time, he becomes interested in Kahoko because of her carefree music. Keiichi also shows interest of her because the music he plays always seems to be stuck in his head. Him and Kahoko usually encounter each other at musical events like concerts, showing of instruments, etc. Kahoko commented that when he smiles, he looks like an angel. He has an older sister, a younger brother and a younger sister. His older sister always sends him costumes to try on.
Recently, in an extra in chapter 62, his big sister Tomomi came to the school and was mistaked for him.