Niina, a member of God Tribe, was worshipped as a deity on her homeland until she is captured and sold to slavery where she is put a magic collar to restrain her and enslaved by Edgar Fromware. After being saved by Rein Shroud, she became his fifth contractual to help him kill her tormentor, Edgar. Niina looks like a child with fox features including fox ears and three fox tails on her back. She usually wears her traditional dress. Niina is a kind person, for instance, for the sake of people she accepts getting enslaved by Edgar. After getting enslaved by Edgar, she resists his lashings and never stops longing for someone who can help her out. When Rein came to her rescue, at first, she was scared because of her trauma but she was touched by Rein's kindness. She always thinks of others' well-being no matter how much horrible a situation she is in. As Rein was breaking her collar to terminate her contract with Edgar which made Rein feel severe pain, Niina shows a melancholic nature and says he should just stop it as no one going to be sad if she dies. But Rein refuses this, replying he'll be sad. This causes her to fully trust Rein and surprisingly she finds his recklessness a unique's trait. Niina used to live in a shrine deep in mountains, hailing as a "goddess". She was glorified by the neighboring villagers and was sleeping peacefully. She lived a peaceful life until Edgar Fromware heard the rumor about her and enslaved her using a magic collar. Since then, she had to face Edgar's violence and torture. She was freed by Rein Shroud, and in the process, became his fifth contractual.