Yu Xiaoyu is the 10-year-old daughter of Yu Molan and Lin Zhixi. She is initially naive, glad to skip school and asks for cartoons. She draws a picture of an angry grey sea and notices earthworms fleeing the flowerbeds. As the situation worsens, she becomes scared and develops a low fever. She refuses to drink the strange filtered water, but her father's sternness forces her to comply. She sleeps with a rabbit doll for comfort. She gradually learns to accept the harsh reality, embodying the loss of childhood innocence in a disaster.