Ops.. my mistake .. will giving sources/info next time.. i think this is from wiki...
Japanese eroge, also known as H-games or hentai games, have their origins in the early 1980s, when Japanese companies introduced their own brands of microcomputer to compete with those of the United States. Competing systems included the Sharp X1, Fujitsu FM-7, MSX, and NEC PC-8801. NEC was behind its competitors in terms of hardware (with only 16 colors and no sound support) and needed a way to regain control of the market. Thus came the erotic game. The first commercial erotic computer game, Night Life,