There is a novel in the Republic of China where the female protagonist temporarily lives in the male protagonist's house. The male protagonist is the friend of the female protagonist's brother. The male protagonist and the female protagonist

I'm not really a fan of online novels, but I can answer some basic information about novels from the Republic of China. According to the information you provided, there is a novel called " Long Lovesickness ", which tells the story of the female protagonist Wu Manniang and the male protagonist Li Lingxiao meeting and falling in love during the Republic of China. Li Lingxiao was Manniang's brother's friend, and there was a subtle emotional entanglement between the two. At first, Manniang was temporarily staying at Li Lingxiao's house. Later, the two gradually attracted each other and began a sweet relationship. The plot of the novel was complicated and the characters were deeply portrayed. It was a classic romance novel of the Republic of China.