Buttobi!! CPU

From MangaUpdates -
This story revolves around the life of Akira, a man who has been saving his money for over three years to finally obtain a computer. Unable to get the computer model he wants he is offered the same model from a shady man in an alley. What happens next is something that will change the life of Akira forever. For he didn’t look at the box closely enough to note that it isn’t Model 9821, it is actually Model 2198, a super advanced gynoid who’s sole purpose is to serve and protect her “master.”