Hiromi Oka  

, 岡ひろみ

A teenager at Nishiko High School begins playing tennis due to admiration for Reika Ryūzaki, known as "Madame Butterfly" because of her elegant style on court. The team gains a new coach, Jin Munakata, who recognizes Hiromi's potential and trains her to excel in the sport. Despite facing mental challenges, Hiromi strives to improve her skills. Nishiko High School is based on Urawanishi High School, where the author attended.