Zhu Nanxu is Zhu Heqing's cousin and a doctor who treats Yu Huan at the private hospital. She is portrayed as teasing and observant, often poking fun at Zhu Heqing's rigidity while showing genuine concern for Yu Huan's condition. She provides medical advice, such as checking Yu Huan's pulse and recommending ibuprofen and warm towels for the fever. Zhu Nanxu has a close, familial relationship with Zhu Heqing, engaging in light banter about his personal life and health. She is meticulous in her medical duties, visiting Yu Huan twice to monitor her temperature and ensuring the caregiver follows instructions. Her demeanor is professional yet warm, and she serves as a supportive figure in the story.
