The movies share similar themes and both feature an unhealthy relationship between the main characters.
So, dude you will get the same the fuck am I even watching, gut wrenching HARDCORE BDSM AND EXTREME, NON CON, DUB CON, and Cherry has a more beating , rent boy, and whipping kink (my favorite) while Dangerous Drugs has a more medical, kidnapping kink. But personally I felt like Gang of Cherry not only had better casting but the plot was kinda messed up but unique and complex. Whereas Dangerous Drugs just literally feels like a porno. Which is both fine with me BTW just thought I'd mention.
Just like Pornographer, Sei no Gekiyaku has some very mature contents. Both are made in Japan and concentrate on an LGBTQIA+ relationship. You could also (in my humble opinion) say that, in both Pornographer and SNG, one takes advantage of the other, leading to a physical relationship and feelings that begin to grow.