Well, many modern novels might also include such elements. However, it depends on how you define 'do sex stories'. Some might be more about the exploration of sexual identity and the impact on characters' lives. For instance, in 'The Color Purple' by Alice Walker, there are aspects of sexual abuse which are used to show the pain and growth of the main character, Celie.
Yes, in some classic literature, there are stories that touch on sexual themes in a more implicit or symbolic way. For example, in James Joyce's 'Ulysses', there are some descriptions related to human nature including sexual aspects which are presented in a complex and artistic way. But these are not just 'do sex stories' in a vulgar sense but rather a part of exploring human relationships and psychology.
In some historical literature, there were stories that were somewhat related to sexual relations within the context of that time's social norms. Take 'The Decameron' by Giovanni Boccaccio. It contains many tales where sexual relationships are part of the plot, often used to comment on human nature, morality, and society of the medieval period.
Chapter 661, "Uninvited Guest", is the clearest early answer because it turns Pei Ye's situation into a concrete plot event. A useful checkpoint is the way the scene starts with A moment later, Zhuola let out a cold laugh, her voice hoarse as she...
Chapter 306, "I Believe Whatever Miss Jiang Says!", is the clearest early answer because it turns Jiang Says's situation into a concrete plot event. The chapter gives readers a real answer by opening on But Jiang Li seriously shook her head, "No, Aunt Zhou, this matter...
Chapter 335, "You would be incredibly fortunate if you could get connected with the merchant family!", is the clearest early answer because it turns Xiao Liu's situation into a concrete plot event. Early on, Zhang, you're overestimating the matter." "Alright then, come in with....
Chapter 477, "Brother Pig, Don't Be Afraid", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. Early on, Alright then, everyone come over and eat while it's still hot." Jiang....
Chapter 475, "Doting on the Man You Love to the Fullest", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from On the other side, Jiang Yan and Shang Shuyue also set off.
Chapter 466, "Are There Really Wild Boars?!", is the clearest early answer because it turns Shang Shuyue's situation into a concrete plot event. It opens with The lady sure acts like a lady, even in 'Wilderness Survival' she...
Chapter 183, "Sacrifice Oneself, Break Them Up!", is the clearest early answer because it turns Wenwen's situation into a concrete plot event.
Chapter 352, "Furong Cake", is the clearest early answer because it turns Liu Suqing's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Finding Liu Suqing's address was not an easy task.
Chapter 473, "Little Hua? What a Joke!", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Su Yinwan completely fell apart after hearing the news in the shower,...