#24-year-old sister, nurse, #21-year-old brother, college student, on a family vacation, meet a pickup artist researching their close relationship. On a hot summer beach, their conversation flows easily—“We used to bathe together, haha,” “Stop walking around naked after the bath, seriously”—revealing their intimate bond. They're then challenged: “Get an erection and stay aroused through a game of strip baseball—win 1 million yen!” The sister claims, “We’re not turned on by each other as siblings,” yet she becomes aroused seeing her brother’s nipples. “Don’t get hard already!” she snaps playfully, but her reaction only excites him further. Instead of removing his underwear, he asks for a kiss. She kisses him like he’s her boyfriend, leaving him flustered and fully erect. Seeing this, she has her nipples teased again, involuntarily responding with pleasure. Electric stimulation floods her with thick arousal fluid, while handjob brings massive squirting. The blood-related siblings dive into forbidden creampie sex. As they lick each other’s genitals, a penalty game orders the brother to keep his cock under control. The sister, turned on by his pre-cum, mounts him, moaning, “So hard… I’m the only one feeling this good?” as she rides him. Their family trip turns into a forbidden creampie frenzy. Even as he creampies her doggystyle, then thrusts into her missionary while holding hands, she can’t climax—but her switch is flipped. Losing all reason, she screams, “Cum in my mouth!” Wait, wait, you two—too many creampies already! Go take a shower and cool off!