I got a second opinion on the legality issue and I'll simply repost what they wrote. Before that though, i'd like to point out that spoilering illegal content does nothing to make it less illegal and law enforcement couldn't care less either way.
First of all, despite what anyone tells you, the first amendment of the U.S. protects ALL "art" and speech.>But, muh obscenity laws!
They're unconstitutional and built on nothing more than subjective judgement. They don't, and never will, carry any actual weight. Even then, there is already (Unconstitutional) laws in place in regards to prosecuting someone for possession of "extreme content" such as "cartoon child porn", and just look at how many cases there actually are of someone getting fined or sent to jail in the U.S. for it. There's only been five known cases. Four were people in possession of actual child porn. The only case where it was BECAUSE the guy had lolicon porn was tried in a military court, and they went after the guy, not because it was lolicon, because it was PORN (Which he wasn't suppose to have in the first place)…
Third, no police force in the U.S. will even WANT to go after it because they KNOW it's harmless and it interferes with their work or going after ACTUAL criminals who commit REAL crimes. Korea and England already suffer from this issue where the police don't have time for "actual crime" because they're too busy arresting people for looking at 2D girls, or posting something mean online: https://archive.fo/OUqfO
On top of that, the U.S. congress pushed through a bill, last year, called SESTA/FOSTA, with the purpose of "stopping online sex trafficking", which even had the DoJ screaming that the bill won't actually solve anything and only make their jobs harder: https://archive.fo/eNz2u
And, that's also leaving out the fact that the one site that both the bills were design for specifically taking down (Backpage.com) was seized before the bill was even passed: https://archive.fo/bgLo0
Long story short, there shouldn't be anything to worry about. There is nothing illegal about 2D and fiction, and people know this.