I think I can recommend Return of the Immortal: My Goddess Sister and Glory of the Phoenix. The former is a novel about urban supernatural powers. The male protagonist is a story about a sister who is protected by seven goddess sisters. The latter is an ancient romance novel. The male and female protagonists are childhood sweethearts. The male protagonist is a young master brother who has a lucky sister. Both books had sister elements, which were very suitable for pure sister-con and sister-con readers. I hope you like my recommendation.π