Biological granddaughter. She is the heir to the academy, he was very stern with her upbringing and molded her to take his place and even aranged her marrige to a teacher at the school, after his stay at a hospital he saw just how much he was forcing her to accomplish and left the school in her hands to run as she liked and let her be happy her way.
Surrogate granddaughter. She is only his granddaughter through his son's marriage to Yuzu's mother. They did not get along when thay first meteven expelling her for a misunderstanding when he saw her and Mei together, but after she saved his life he appologized to her allowed her to come back to the school.
His son. Shō left 5 years ago (in the manga) to go on a world tour. He has since given up all right to run the Academy after his father.
His daughter-in-law. It is unknown if they have ever met.
The students seem to fear and respect him and his authority