Honoo no Haramase Tenkousei by SQUEEZ - Adult Sex Game

You start off as a young student who has recently comes across an adult video. This inspires you to someday take over the world in order to have all the women of your choice for the taking. However, the world is a pretty big place--you'll have to start small. You begin your conquest by wooing/scouting all the girls in your class! Now some years have passed, and you're all grown up. In a brilliant twist, you've turned your friends (along with some of your new encounters) into your own personal harem! Sounds like a nice start for world domination.