The Little Senior Sister from an Immortal Sect in the Stars

During a battle between immortal sects, Huilian, the daughter of the leader of the Rogue Cultivators' Alliance and a junior sister everyone called Little Senior Sister, was caught in the crossfire. She transmigrated to the interstellar age and became a lotus demon. While cultivating, she discovered that a formation inside her seemed to be controlling her cultivation and making her body regress. Little Senior Sister broke free of the formation and cultivated a human form. Before she had a chance to hide from humanity, she discovered that this interstellar world was already one where humans and demons married. Little Senior Sister discovered that some powerful demons regressed after using their abilities, eventually reverting to their original forms and gradually losing their vitality. Together with the male lead, whom she met at school, she investigated how to slow the regression. They discovered it was caused by human interference, and ultimately found the mastermind and freed everyone afflicted by it.