HUNTB-445 "You're trying to put it in, aren't you? No way... we only promised to rub!" While doing cosplay sex with a sister who has overly large breasts, I suddenly experience deep penetration! Losing my virginity & experiencing raw insemination...

I'm the only virgin in my class, and it's been bothering me so much that I've been depressed, my grades have dropped, and I've even refused to go to school! My sister, who is incredibly kind, noticed my strange behavior and comforted me! She became my first sexual partner! At first, I clumsily moved my hips in a dry hump as instructed, but it felt so good that midway through, I started thrusting with all my might! And then I ended up inserting it! I broke the promise of dry humping… But as a result, I became the ultimate playboy in my class, leapfrogging 10 levels!