APNS-233 My younger sister was made into a tit-fucking slave by my seniors... - First love

His older brother, Ryuta, is somewhat of a recluse, and has been having a sexual relationship with his younger sister, Nenne, a female student. - Nenne knew it was wrong, but she couldn't resist the kind Ryuta, so she continued to perform oral sex on him, even though she hadn't penetrated him in years. - One day, Ryuta's friend from his school days, Kameda, comes to visit. - Kameda took note of Nenne's big breasts, used her relationship with Ryuta as a joke, and was planning to use Nenne's relationship with him to blackmail her...