You are the older brother of a younger sister who is just starting to learn about sex, and you can develop her body over the course of 30 days. Increase your sister’s favorability by going out with her, and increase her lewdness through late-night touching to make her fall in love with you! The ending changes depending on your status and progress. Spoiler Synopsis Due to his parents’ sudden trip abroad, the protagonist has to live alone with his rebellious younger sister for a month. One night, he peeks into his sister’s room and finds her struggling to masturbate for the first time. As her older brother, he decides to develop his sister’s body in the middle of the night in order to release her sexual desire. The naughty 30 days with his sister begins!
