There could be indie or self - published novels with such a concept. It might be a story that uses this unique idea to explore themes like the unknown within ourselves, the power of the subconscious, or the existence of hidden magical forces. For example, it could be a story where the girl's levitation while sleeping is a sign of her untapped potential that she has to learn to control as she grows in the story.
Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
Perhaps it's a spiritual phenomenon. In the novel, her levitation while sleeping could be related to her spiritual awakening or connection to a higher power. It could be that she is being lifted by some spiritual force as she sleeps, which is a sign of her special spiritual journey within the story.