After receiving the note, Yu sin entered the drug den alone in order to save An Jialu. When he entered the drug den, he was poisoned with a mysterious poison by two strange men in black. However, due to the side effects of drugs, the sinful body returned to the state of children. In order not to implicate people around him, he changed his name to Liu Xing, lived in Liu Mei's home, and finally became a family with Xia Donghai, Xiaoxue and Xiaoyu, from which he got to know Mouse's elder brother Keyboard.