A mysterious past (Harem x male reader)

In this story our main character, Y/n L/n, was waken up from his dream and soon his dream of having a harem filled with girls that he liked from anime, marvels, DC, and video games. But they didn't know that he has a sad past of a horrifying B.O.W. named Nemesis

So it won't have DBZ characters and I'm sorry for that.