In the dim light of their shared room, the devout sister, driven by an insatiable curiosity, tentatively reaches out to stroke her brother's sleeping member. She's haunted by religious guilt but can't resist the allure of his untouched cock. As she gently pushes his foreskin back and forth, he stirs, forcing her to freeze. She waits, heart pounding, before resuming her exploration, feeling his shaft harden under her touch.