Modern medical student Su Xiaoli unexpectedly transmigrates into a fat orange cat in the demon realm, kept by the demon emperor Di Yeming who is afflicted with a gu poison. Relying on her medical skills to ease the demon emperor Di Yeming's pain, she is forced to take human form during the dust-washing banquet, goes through a crazy weight-loss journey and ultimately transforms into an peerless great beauty, shatters Luo Wanqing's schemes, and stays with the demon emperor to rebuild the peace of the three realms.