Hideo Harada 原田秀雄

Hideo Harada is the head of the Shiranami Society for karuta that Chihaya and Taichi are part of. He used to teach Arata as well, while Arata was in primary school with Chihaya and Taichi. He taught Chihaya throughout Junior High School and is currently mentor to both Chihaya and Taichi. He is also a medical doctor and married.

Harada Hideo is portrayed as a kind man with a deep and insightful knowledge of the game of karuta. He states that he teaches his students offensive karuta, which aims to take cards from the opponent's side. He is extremely competitive, whether on behalf of his students or as a competitor himself, or even as a figurehead, representing his karuta society, and is his students' staunchest supporter.