Sumire Ryuuzaki

As a dedicated math teacher and coach of Seigaku's tennis team, this character played a pivotal role in developing Nanjiro Echizen's skills. She holds a significant place in the family as Sakuno's grandmother. Despite a friendly rivalry with her former mentor, Banji, she is known for her passionate coaching style and is a reliable mentor. She fosters warm relationships with her students, often engaging them in group activities like bowling and beach volleyball.