The Lewd Older Sister

The story revolves around the protagonist, Inane, a high school student who is feared by his classmates for his exceptional fighting skills. However, his life takes an unexpected turn when he discovers a mysterious journal belonging to a girl named Aniki, who is rumored to be a lewd and immoral person. As Inane delves deeper into the journal, he learns more about Aniki's thoughts and feelings, and their relationship gradually develops into a complex and intimate bond. Through the journal entries, the reader is privy to Aniki's innermost thoughts and desires, which challenge Inane's perceptions of morality and relationships.