FNS-087 - Tempted by Girlfriend's Sister's No-Panties Appeal, Losing it to Her Tight Anal Licking

Visiting my girlfriend's house for the first time, I meet her model-like sister, Ranran. Later, while heading to the second floor, I peek through her open door to find her lying there without panties. Noticed and teased, Ranran asks, 'Were you peeking?' while sticking out her rear and tempting me to lick her anal. I end up indulging in her pheromones right under my girlfriend's nose.