For a serious and timid sister who always listens to everything her virgin brother says, when he persistently begs, "Let me have sex!", she reluctantly agrees, saying, "I won't actually insert it, but if it's just practice..." As the sister, who is constantly touched, experiences kissing, breast fondling, and hand stimulation, she becomes so wet that she develops stains on her panties. Getting carried away, the brother forcefully inserts his penis! He vigorously thrusts his hips so hard that it seems like her vagina might break, ignoring her protests, and repeatedly ejaculates inside her numerous times!