[Himeno Mikan] Sujitorori - Lolita and Wet Slit {Mistvern}

An older brother's after-school babysitting duties spiral into something far stickier when his little sisters Akari and Natsu decide playtime means him, and he discovers their tiny bodies grip him tighter than any self-control can survive. Akari bounces eagerly through a baby-making lesson while nervous Natsu begs him to be gentle through her first time, and he abandons the final step he swore to hold back on, pumping both girls full until it leaks out of them. A hasty kiss seals their secret just as Mom calls everyone to dinner.