After her biological family is killed by a Kutou gorilla group, Fuka is orphaned. She is later taken in by a farming family along with Yuma, a boy who is also offered housing for farm work. They are abused and frequently overworked, which hardens Fuka.
She is spunky, bold, and androgynous, often being mistaken for a boy. A feminist, she believes that men and women should be equal and scoffs at the limitations on women, opting to simply dress, act, and speak freely regardless of class or sex. Fuka is also not afraid to put people in their place, especially Yuma whenever he bullies Tamahome. Her feelings towards the celestial warrior are also hinted at throughout the light novel.
Despite her unpolished appearance, Fuka is shown to be kind-hearted and selfless. As a child, after Tamahome's mother dies, she makes trips to the other side of the mountains to retrieve herbs for his sick father and takes food from the farm to feed his starving siblings. She is also a very talented singer and finds a temporary but rewarding job as a street performer.
|“||So what? I don't think that [being a woman] should make a difference. And I'm sure you don't think it makes a difference either, right?
— Fuka, Shugyoku Den Chapter 3
In Hakuko, Fuka first comes to Tamahome's aid to drive away a group of local children, lead by Yuma, after their relentless insults escalate into violence. Being the only person Yuma cares for, he steps down. Fuka tells the young warrior to stand up for himself and as the years go by, her encouragement turns to affection.
After Tamahome's training with Tokaki and the death of his mother, Fuka makes a habit of visiting his home with food or medicinal herbs for the suffering family.
Tamahome then decides to head off to Eiyou for work and the outgoing Fuka sneaks off to follow him. When she reveals her plan to stay with him, Tamahome refuses to travel with a girl. But Fuka, determined to find work, convinces him. They are soon discovered by Yuma, who tags along to protect Fuka, and the trio head to the capital.
Along the way, Fuka watches with annoyance as the two boys compete against each other to see who can make the most money by doing odd-jobs. Fuka finds a nice step up as a street performer, captivating the citizens of each village they pass through with her soft and light voice. With her winnings, she supports the other two, who are too competitive to earn wages.
After hearing of a murderous sorcerer called Mimadou, the two boys are determined to catch him for a reward and they follow the trail of bodies to Eiyou. There, Fuka encounters a wealthy girl called Bihou Kyou and saves her from Mimadou's monster, lunging to fight before Yuma interferes, leaving Tamahome to finish it off. When the warrior is hired by Bihou's father, Senmei Kyou, to protect her, he gives his large earnings to Fuka to pay off the debt he owes for her taking care of his family. Fuka views this gesture as someone taking pity on her because of her family situation, not because he is grateful.
She leaves to clear her head and goes for a walk in the outskirts of the city. There, she meets a smiling monk with strange powers and teleportation magic. She asks him to teleport the money to Tamahome's family in Hakuko and, after she passively mentions his celestial destiny, the monk agrees and disappears.
Fuka returns and meets Yuma in Senmei's garden while Tamahome is stuck on duty. He tells her that the warrior's new employer is bankrupt and he suspects Senmei has alterior motives. That night, when Tamahome and Senmei leaves the mansion, Yuma tries to follow them but is stopped by Fuka, who wants to join. Fearing for her safety, Yuma knocks her unconcious and follows Tamahome. Fuka is found in the garden by Bihou's servants and brought to the wealthy girl. She critsizes Fuka's appearance before dressing her in beautiful robes and jewels. Suddenly, Mimadou's men storm the mansion. They shove a surprised Bihou aside, and take Fuka away, mistaking her for the Kyou daughter.
Yuma and Tamahome return to the mansion and split up in search for Fuka, who leads Yuma to her location with her singing voice. When they are reunited, he gives her a Shugyoku jewel, symbolizing his love for her. With his guard down, Yuma is put under Mimadou's control and, when Tamahome finds them, Yuma attacks.
After an intense battle, Yuma breaks free from the spell and sacrifices himself to save Tamahome and Fuka. Though his wounds appear to be fatal, he survives, a testament to his strength that he never truly showed Tamahome. He and Fuka, who is impressed by his development, then travel back to Hakuko to start a home, feeling content in Tamahome's progress as a Celestial Warrior-In-Training.
By the time of the Original Series, the couple is living peacefully in their cottage while their friend continues to make a living in the capital.