Narantuya began changing into a horse-girl in her tenth year, a year after she had realised she could communicate and control the animals around her. She was afraid of her transformation, and her family were also frightened. They called the doctor, and he, in turn, called an associate in China. Within a month, Narantuya was flown to Beijing where she underwent intrusive investigations without her parents' knowledge. She was isolated from everyone until she met Zhang Li, a veterinarian who had taken an interest in the girl. The two became inseparable, and Narantuya gradually began to improve in her health and disposition. Under Li's care, the Mongolian girl came to understand that her parents had abandoned her, that she was now obligated to work for the Chinese government and that if she worked hard and did what she was told, she would grow up to be a beautiful princess.

Of course, Narantuya grew to suspect the motives of the Chinese. She grew out of the dream of becoming beautiful just because she was doing what she was told. She learned to control her new body and to actually enjoy it. There was a freedom in being able to gallop at high speeds, and she was given regular holidays in the mountains and plains. When she was invited, or required, to join the Immortals, Narantuya saw it as just another step in her progression to adulthood. She was twelve when she joined the Immortals, but she had grown more mature and intelligent than her guardians realised. She maintained a kind of internal journal with the animal world around her: she would converse with them and tell them what she was living through. She even dared to tell them her dreams of freedom, of returning to Mongolia where she would live freely among the horse people.

The celebrity status she received from being a part of the Immortals surprised her, and shook her from her depression. She was welcomed by the public, and they saw her horse body as something wonderful, something to inspire the other young people. Narantuya began to question her desire to return to Mongolia. Perhaps she could find happiness here?

Narantuya is simultaneously naive and cynical. In many ways, she is older than her thirteen years, but the onset of celebrity status has reignited childish desires and expectations in her which she thought were long gone. She is a follower, afraid of getting into trouble from her team leader or the Government officials. She wants to be left alone, but at the same she wants to be accepted and loved by everyone.

“I don't eat grass, no. But thanks for asking. Ever had a hoof sandwich?”

Horse is a centaur-like being, having the top half of her body human and the lower half horse. She is able to run at impressive speeds and possesses great strength, mostly in her legs. In addition to her horse-like abilities she is also able to communicate with animals.

Narantuya appears to be a teenager from her head to her waist, and a dark brown horse below that. She wears her dark hair in twin braids down her back, and wears a loose-fitting red t-shirt with the horse symbol. When she is not on duty, Narantuya wears oversized t-shirts, or on occasions when she is alone and in the wilderness she rides without the burden of clothes.