My girlfriend and I are getting married. Today I visited her house and met her sister, Riho-san. I've also been shown her photos by Kurumi before, and I know she's the idol I've been idolizing for a long time! She is even more beautiful and charming in real life! She seemed to be trying to invite me too. She let me see her beautiful big boobs, blow me a blowjob, and more importantly, she let me fuck her without a condom! Even when I was about to get married, my girlfriend still forced me to wear a sack, so when Riho-san invited me like that, I couldn't stop! Our secret relationship continued like this until the wedding day. My sister and I planned to have sex one last time and end this relationship. But Kurumi didn't expect to find out. Discovered but we didn't stop, I ejaculated a lot of sperm into Riho's body right in front of Kurumi. I'm not sure what the wedding will be like, but I know my bride will no longer be Kurumi but her beautiful older sister...