Orphaned at a young age, Naoto was discovered with amnesia following the brutal murder of her parents, which left her with a distinctive X-shaped scar on her chest. She was taken in, raised, and trained by a swordsman she believed to be responsible for her parents' death. He named her Naoto after someone from his past but never disclosed his own name. Upon his death, she learned that her parents were killed by an assassin who shared her name—the original Naoto. After this revelation, she uncovered her mentor's identity as Fuyumine and adopted it as her family name. It appears she developed some affection for him during their time together, even referring to him as "father" after his death. Since then, Naoto has befriended Nill and followed Haine to uncover more about Fuyumine's history, the first Naoto, and seek revenge. She wields the katana inherited from Fuyumine. Among herself, Badō, and Haine, she seems the most gentle and least inclined to kill.
Naoto doesn't get along well with Haine, and much of their time away from battles is spent glaring at each other maliciously. This likely stems from Haine's extremely brutal and cruel tactics in combat. Often, Badō must mediate the tension between them. However, when confronting enemies, they are shown to be lethally effective when working together.
