Sayaka Mine, daughter of Raizo and Shizuka Mine, begins as an ordinary Tokyo middle schooler. Her routine life shifts dramatically when the wild Yaiba Kurogane arrives and moves into her home, pulling her into his supernatural adventures where she evolves from a reluctant bystander to a vital member of his group. Her heritage becomes pivotal during the Kaguya Arc, revealing her as the descendant of the Dragon God Priestess. This makes her the key to restoring the Moon Empress Kaguya's youth, placing her at the conflict's center as Kaguya targets her youthful essence. Sayaka possesses long brown hair, typically secured in a high ponytail with a pink hairclip. She is often depicted taller than Yaiba and noted as beautiful or cute. Her primary attire is a school uniform: a blue skirt, white sailor top with a red bolero tie, pink socks, and white sneakers. Casual outfits include a salmon pink sweater over a light yellow button shirt with a sea green skirt, later replaced by a purple hoodie over a yellow shirt with an orange skirt during the Kaguya Arc. She wears a hot pink one-piece swimsuit and sleeps in pink polka dot pajamas or a light pink kimono dress. When Kaguya drains her essence, her hair turns white, her skin becomes pale and wrinkled, and her eyes are obscured until her resolve returns. By the series finale, she appears taller and more mature. Energetic and assertive, Sayaka often reacts with physical discipline towards Yaiba or Musashi Miyamoto for perverted or arrogant behavior. Though bossy, she possesses a fundamentally noble heart and decisiveness in crises. She develops romantic feelings for Yaiba, admitting them only in the epilogue. After Kaguya's attack leaves her aged and depressed, she regains her determination when Yaiba reaffirms her inner strength. Her role evolves across arcs. Initially a bystander or support, she temporarily wields the Water Demon Longsword (Suima no Tachi) during the Yamata no Orochi Arc, a katana-like weapon of solidified water generating water attacks, though her combat skill remains limited. She plays a pivotal role as Kaguya's target in the Kaguya Arc, suffering temporary physical decline. In the epilogue, set three years later, she attends high school alongside characters from Magic Kaito, indicating a return to normalcy. Beyond the main series, Sayaka appears in crossovers. In *Magic Kaito*, she intervenes when Kaitou Kid enters her room and tends to Yaiba's injuries after his fight with Kid. In the *Detective Conan* OVA *Conan vs. Kid vs. Yaiba*, Kaitou Kid hypnotizes her with a kiss to reveal a sword's location. She also features as a sprite in a video game within *Detective Conan* Chapter 1039. Trivia notes that "saya" in her name means "scabbard," symbolizing her complementary role to Yaiba ("blade"). She shares a voice actress with Kir/Hidemi Hondou from *Detective Conan*, another Gosho Aoyama creation.