This is a very different story compared to the normal manga, it is a hentai. It is not a harem as most might misjudge it as, but i would put it in the love triangle realm. This is because there are only two love interests and no more. There is a huge sexual component but that is not what a harem is. I do think this is not a manga but it is definitely very good.

Now this guy who is bad with girls, gets drunk one night and decides to pee on a tree well to his misfortune there was a demon who needed to be sealed close by and the angle tasked with this misses the ball and hits his right nut. >.> ~WHAT? Lo and behold he now has a demon sealed in his testicle and needs to not cum for a month; but the way they show the time-line is terrible. Now he has the entire demon realm(Hell) going after him trying to make him cum.

Oh what else happens during this time his dream girl makes the first move and asks him out, now I feel bad for him. Anyway if he comes humanity will be destroyed and demons will retake earth. When his girlfriend get drunk she turns into a nympho, to prevent an accident from happening a loli is sent to make him cum, he cuts her a deal for his soul to stop anything from happening. This is a weird relationship i'm not going to get into as it will take to long.

Long story short, he holds out longer than he needed to, save humanity, fights major demons including Satan, loses his dream girlfriend, and gains a loli girlfriend. Satan is a female and falls in love with Michael after he bends her will to his sexual prowess.

I found myself smiling during most of the story baffled by other parts but liking it overall unlike the two other reviews(1 negative and not finished by reviewer/ another maxed out rating which this is not)[as of 4/9/16]. Worth the time to read might take a week if read sporadically only 40ish chapters.