Natsu is the adopted daughter of Jūzō, the owner of the Sugaya merchant house. Orphaned at a young age, she was raised by Jūzō, though she often struggles with feelings of not truly belonging or being loved because of her adoptive status. Rather than being a quiet or gentle merchant’s daughter, Natsu is strong-willed and sometimes sharp-tongued, possessing a lively attitude that masks her deeper insecurities. She first becomes acquainted with Jinya, the demon hunter, when he is hired to kill a demon that has been hunting her. Over time, their relationship takes a tragic turn when Jinya is forced to kill Jūzō after Suzune transforms him into a demon through an enchanted drink. This event causes Natsu to grow to hate Jinya and distance herself from him, marking a significant emotional turning point in her life. Her motivations are largely rooted in a desire for acceptance and a stable family, and her role in the story is closely tied to the consequences of the demonic threat and the personal cost of Jinya’s mission. She is around thirteen years old at the time of her introduction. Natsu’s development involves navigating the pain of loss and betrayal, growing through close friendships and heartbreak. She does not possess any special supernatural abilities; she is a regular human whose significance comes from her emotional connections and the moral weight she carries within the narrative.