Miniature girlfriend's younger sister secretly having unprotected sex under her skirt - reverse NTR (Netorare, having a girlfriend but still getting continuous ejaculation outdoors) NHDTB-862

What I initially thought was my introverted girlfriend's younger sister turned out to be incredibly provocative in the "wilderness"! She exposed her underwear, asked for a kiss, and aroused an erection!! After learning that she had never had unprotected sex with her boyfriend, he went berserk! Even though his girlfriend was nearby, he didn't care and penetrated her without a condom under her skirt! Unable to resist her innocent, bouncy hips, he ejaculated inside her! He was even pinned down by his unsatisfied sister and had sex twice...