Okane ga Nai

Okane ga Nai and Level C are essentially the same story told differently. In both cases we have a rather thin plot involving a strong shounen-ai element that includes sex as rent, as odd as it may seem. While not overly graphic in terms of content both titles have no qualms in being pretty in-your-face. Okane ga Nai has more angst and occasionally violent while Level C is sheer fluff but they are remarkably similar.  

If you love pairings with one male very feminine and a cute but also yummy yaoi then you'll love this. 

both are about having to do sexual things essentially in exchange for cash or to pay back debts. while okane ga nai has more of a plot to it and more substance, they are essentially the same. SHOTA!! 

Apart of the yaoi/shonen ai, romance and comedy, both have a girly uke but keep in mind that Okane Ga Nai is more explicit. 

Both of them have to deal with gang and violence, also they are both yaoi but I think Tight rope is much less intense than Okane ga Nai. Also in my opinion Tight-Rope has much better Art.  

What would you do to get rich? Both Okane ga Nai and Meisou-Ou contain a young man (Two in Meisou-Ou Border) doing various shady schemes for money. Not only are there slight bouts of comedy within a dark situation, there is nudity and a cast of nearly all men. They both are very morally grey shows; you will either enjoy it or hate it. 

dealing with underworld organization, rape, and betrayal for both uke sides 

Man on Man Relationship. Although one is a student and the other isn't. 

Both are yaoi anime where seme is infatuated with a much smaller, weaker uke and forces him into relationship. Uke appears to be unwilling but does nothing to escape the situation. 

Both are crappy romance OVAs that have poor excuses to show some sexual harassment. And there is barely any romance at all. 

Kind of the same type atmostphere and corprate feeling 

As other has said, this is only Yaoi and not hentai but it's very cute(+ someones getting raped) It includes a man and a boy in a relationship with money in play but it's very romantic too. 

Relationship between a young male and an older man. Both of the young males try to make excuses saying that they're not in love. Sexual desire for each other. Lots of awkward situations.