Lost in Endoria: A Monster Girl Harem

What would happen if a frail nerdy guy got transported and isekai’d into a world full of monster girls?

And what would happen if they all figured out that this nerdy guy, the only male in their world, has the power to make every monster girl strong by eating his semen?

Will they free him and allow him to return to his world? Or will they lock him up and use him to strengthen their powers to dominate the world?

And what will you do if the only one who can help you return to your world is gone? Will you look for her? Or will you traverse the unknown world alone to find your way back home?