Please help find the doujinshi I read like two years ago, this are all the details I remember:
_ Omegaverse / Mpreg
_ Only males island
_ Public night ritual/celebration where younger boys (kinda high school students/shounen) get impregnated by older boys (some were their teachers but like just around 20-25yo and they were kinda buffed)
_ The ukes had a symbol around their belly button that formed a circle, this symbol is more visible during this celebration bc it’s the signal that they are ready to get pregnant.