Reika Ryuuzaki, known throughout Nishi High School by the nickname Madame Butterfly, is a senior and the star player of the school's tennis team. She earned her moniker from the graceful, butterfly-like elegance of her playing style, which makes her a formidable opponent and a source of admiration for her peers. Coming from a wealthy and influential family—her father serves as an executive on the tennis association board—she carries herself with the poise and pride of an upper-class upbringing. She serves as the student council vice president and is deeply committed to maintaining her reputation as the school's top athlete. Beneath her composed and sometimes distant exterior lies a strong sense of justice and a compassionate heart. She initially takes Hiromi Oka under her wing, treating her like a younger sister, but when Hiromi begins to receive intense coaching from the new coach Jin Munakata, Reika's pride is challenged. She experiences jealousy and a fear of being surpassed, leading her to act coldly toward Hiromi for a time. However, her core motivation is not merely personal victory; she believes in upholding the dignity of the sport and, eventually, in helping Hiromi reach her full potential. As the story progresses, Reika evolves from a rival who sees Hiromi as a threat to a mentor who deliberately passes on all her skills in a final high-stakes match, purposefully showcasing her entire repertoire of shots as a gift to her junior. Her relationship with Hiromi deepens into a genuine friendship built on mutual respect. She also has a complex connection with the male tennis player Ozaki Isamu, who admires her from afar; the two share a quiet, emotionally charged moment at the beach, which marks the beginning of Reika's openness to receiving affection. Her development is marked by a gradual softening of her rigid pride as she learns to accept that Hiromi has surpassed her, and she ultimately becomes a key supporter of Hiromi's international ambitions. On the court, her notable abilities include a powerful serve, precise groundstrokes, and an overall elegance that makes her game look effortless. She is a complete player, but her greatest strength may be her unwavering mental fortitude and her capacity to inspire others through her grace and dedication.