Cherry & Gal's↑↑

Both are about a cute shota having lots of intercourse with two sexy onee-chans, for both first episodes, the second one of Cherry & Gal's involve another shota and onee-chan, but it's still the same sub-genre. 

Both are about really young boys messing around with pervy onee-sans, MonMusu Quest! Is of course completely about monster girls, but the part about mature and big chested girls molesting cute shotas is strong in here and so is in Cherry & Gal's, which has all of the girls on the gyaru side. 

Sexy and voluptuous onee-chans can't resist the cuteness of these shotas, they must make them feel good at any cost. Yeah that's pretty much what both of these are about, one is in school with gyarus the other a reimagined version of Saiyuuki, enjoy.