My sister is kind to me, a shut-in, and is serious and pure. But she's a slut who can't refuse when invited! She invites a man over when our parents are away and has sex with him! When our parents go on a trip, she invites several men over and has an orgy! I was secretly taking pictures of my sister having sex, but... I finally couldn't just take pictures, and I wanted to have sex with my sister! When I told her, she accepted me, although she had mixed feelings! Now she's my personal slut. This is the record of that.