NHDTB-059 - I turned my premature brother into a beast and now I can't escape his relentless thrusts

Aoi Mizutani, Ai Minano, and Nonoka Izumi—the three of them teasing their younger brother with playful curiosity is top-tier. The way they drive him to climax in the second half is also great. It features the classic 'bed-back' position, and there's a clear distinction between the fun of the first and second halves. I really hope they turn this into a series. Personally, I liked Aoi Mizutani the best, but the other two were also excellent. I wish I had sisters like them!