Total Recommendations: 12
The biggest and most obvious similarity between these two titles is the presence of a protagonist who can swap genders. Both protagonists obtain their ability unintentionally, have no control over it (a "trigger" forces the swap to occur), and even try to cure it. We see how their ability effects their everyday lives, including awkward scenarios, misunderstandings, and male characters falling for them. However, there are some notable differences such as the lack of rivals/enemies in Change-De. And perhaps even more notable, the fact one is pornographic while the other is not. Personally, I prefer Ranma. It has much cuter characters, it's funnier (without having to be crude), and it's super long. So this recommendation is mainly intended for the people who read Change-De. But maybe Ranma fans will enjoy the other if they're interested in seeing what an adult version of Takahashi's manga might look like.
Sex Taxi and Keibiin are mature anime about men blackmailing women in order to get them to sleep with them. In both works, the protagonist is an individual who feels no remorse towards his misdeeds. And in both works, the protagonist's occupation plays an extremely crucial role in achieving his goals. While some differences are present, the two are more similar than they are different. They're so similar that I'd say very little would change if you were to swap the protagonists. However, I think Sex Taxi executed the blackmail plot much better than Keiibin.
While it seems most recommendations on this site are meant to go both ways, this is more of a one-way recommendation. If you enjoyed Kijutsushi x Majutsushi, I'd consider giving the long-running Detective Conan a try. The latter may not have any sex scenes, but what it does have should be more than enough to make up for this one insufficiency. As for the similarities between these two works, there are several. Ignoring the sexual content, both are essentially about people trying to solve cases. Both have a self-proclaimed team of detectives working together. Both have characters making crazy deductions (sometimes crazy in a funny sense, other times crazy in a ridiculously smart sense). And one of the characters, the Phantom Magician, is similar to Kaito Kid, a recurring character in Conan. Really though, the big similarity is the mystery aspect. So if you liked that about Kijutsushi x Majutsushi, as mediocre as it may've been, that should be more than enough reason to consider Detective Conan.
Koushoku Shounen no Susume and Shounen Shikou are lengthy, anthological works of pornography. The art ranges from the adorable to the mildly perturbing. All of the sexual situations depicted involve individuals of the same gender. And while the chapters are self-contained for the most part, characters do occasionally reappear for a second (or even third) chapter. The similarity that stuck out the most to me, however, is their tendency to get Rabelaisian at times. Characters do some of the strangest things with their reproductive organs, and there are parodies present that you would have a very difficult time finding outside the genre. I can’t say I was entertained by most of what I read, but there is one thing I can say: these two manga are pretty damn fun at their best. Oh, and if you think a character’s a girl, there’s a 99.99% chance she’s actually a guy.
As a whole, these manga don't have much in common. However, "Sproingy Stick" and "Defender of Juiciness" are extremely similar. The former is an allegorical story about a man who suddenly finds penises sprouting all over his body; the latter depicts the life of an enigmatic superhero called Penisman. The imagery is bizarre, the humor is anatomical, and I doubt any country other than Japan would even consider publishing something like this. It's the people who love male anatomy that have the most to get out of these pornographic titles.
The most obvious similarity between these two titles is the fact they involve train molestation. They have much more in common than just that though: the protagonist is trained by someone much more skilled than him, a character is accused of a crime he didn't commit, and a female goes from innocent to perverted. And most importantly, the humor primarily comes from ridiculous dialogue/situations. The molester on a train genre has never had it this good.
If you loved the humor in Golden Boy, Ogenki Clinic is the next best thing. Both works are outrageous, hilarious, and highly unpredictable (the latter to an even greater extent). The jokes frequently pertain to male anatomy, bodily fluids, and bizarre fetishes. Then there's the characters—they do, say, and think some of the most ridiculous things. Consequently, I was often left wondering what crazy thing was going to happen next. Golden Boy may not have as many jokes as Ogenki Clinic, but it sure has much more going for it than humor. Overall, I'd say blue comedy doesn't get much better than this.
Both of these titles contain raunchy, outrageous humor. Kounai Shasei is actually the most outrageous anime I've seen to date, but Oppai no Ouja 48 has the most outrageous scene I've come across in this medium. Although the former doesn't have as much fornication (the most appropriate term I could think of), it makes up for it with huge doses of humor. And the latter doesn't have nearly as much humor but tries to compensate for it with excessive fornication. Regardless of the amount of humor, I found both of these anime to be hilarious.
So what could an anime about a rapist have in common with an anime about the milk of life? Not much actually. They share one thing though, and that's the presence of an extremely absurd plot. In Rapeman, we have a superhero who delivers justice through penetration. In Marine a Go Go, we have a heroine trying to make the world a better place by collecting a certain bodily fluid. The synopses of these anime are ones that make you think, "This sounds stupid." These are probably two of the craziest hentai titles you'll ever see.
Seemingly innocent characters are stuck in an environment where people are motivated purely by their own selfish desires. Heinous acts are committed, and those responsible don't even try to comprehend the severity of what they've done (the endings are sure to leave you speechless). The struggle depicted is extremely similar as well. Adolpho is forced to choose between priesthood and pleasure; John is forced to choose between butlership and pleasure. Corruption, innocence, and sexual discovery are all themes these two titles share. Ultimately, the question being raised is the same: What is the toll sex takes on the innocent?
Ruthless savages: That's what men are depicted as in these titles. Consumed by lust, they don't hesitate to make the lives of others miserable. Both morals and emotions have disappeared without a trace. In one, the source of the problem is society. In the other, the source of the problem is in the roots of human nature. These two titles wallow in depravity, but that's part of what makes them tragedies. I felt uneasy watching these titles, and that's not something I can say about most hentai.
Rance and Gokudo are two extremely similar protagonists. Despite being the heroes of their respective anime, neither of them behave like one. The two are cocky, complete idiots, obsessed with women, and care only about themselves. Of the two, Rance is arguably worse. Rance is essentially what you'd get if Gokudo became a few years older and turned into an even bigger bastard. Although their characteristics may not be good, I found the two of them to be extremely likable bastards.