Okay, as a Big Utena Fan I really gotta lock in and advocate *against* Utena here. For several reasons.
1. Not only is the manga out of print, but one of the volumes is *nowhere* online (not in English, anyway). There was supposed to be a reprint of the deluxe boxset (which contains the original 5 volumes + the Adolescence manga - that's the one that's impossible to find - but does NOT include After the Revolution) like three weeks ago but it got delayed by like two months. If you want to read this manga, you are going to have a bad time. In particular, if you consider the Utena manga to be 7 volumes, you're going to be pulling teeth tracking down volume 6 (Adolescence), because again, it's not even online (unless you speak Spanish)!
Right now *only* ways to read the manga are to either A. try your luck at the secondhand market (which gets expensive - I've seen listings go for hundreds of dollars, and Adolescence is especially tough to find so you pretty much have to get the boxset - and AtR is still sold separately), B. read a shoddy scanlation (it is not very good, especially the early chapters - it's also tedious to even find a complete translation of the original 5 volumes, and I haven't seen Adolescence in English *anywhere* online. AtR *does* have good scans that are relatively easy to track down, but that's literally the last volume), or C. learn Japanese (or Spanish, if you're a dedicated pirate). This is not an accessible item for the vast majority of people who would be interested - it's not even easy to pirate.
2. It is, frankly, a mistake to treat the first five volumes (parallel to the 39 episode TV anime), the Adolescence manga ("volume 6" - an adaptation of the movie), and After the Revolution ("volume 7" - a 20 years later epilogue) as one continuous story of 7 volumes. An understandable mistake that no sane person would be mad at you for making, but an error nonetheless. The first five volumes are their own continuity, Adolescence is separate from that. Same goes for the 39 episode TV anime and the movie (also called Adolescence). They are companion pieces, but as far as continuity is concerned they are mutually exclusive. You cannot reconcile these differences, and frankly it'd be missing the point to even try. They are all different takes on the same premise with some of the same core beats shared between them.
As for After the Revolution, that one picks various bits from every other piece of Utena media (and different Utena media actively contradict each other), so it's not really a coherent sequel to any of them. Not the show, not the movie, not even the 5 volume manga, despite expecting you to be familiar with all three. It is its own beast.3. The manga (as in the first five volumes - Adolescence and AtR are their own separate things) is, quite frankly, the *worst* way to experience Utena. It's not the worst read in the world on its own, but it is very drastically different from the anime in a way that is *guaranteed* to disappoint you if you're only familiar with how hyped up the anime is.
The story and themes are very watered down (or rather half-baked, as it was made while the show was still in pre-production) and it's not even that gay (at least by comparison - this is in part because the mangaka, Chiho Saito, simply could not comprehend a love story between two women that does not end in tragedy being publishable in the late 90s. she actively tried (and did not succeed) to push back *against* the anime and film being gayer because she was certain it would be miserable. yes, really. the only reason people are pretty sure she's *not* homophobic is because the Adolescence manga has an unambiguously gay happy ending).
The only thing I can honestly say the manga has going for it is the artwork is gorgeous, but you can't carry a manga off eyecandy. You would have a better time going into the musicals blind and I am not kidding.
TL;DR: the manga is nigh-impossible to get your hands on in consistently decent quality, and is not only inferior to the show (it is overly reliant on the tropes and conventions the show routinely criticizes, and more specifically you can kinda tell that it was written by a girlie who thought everyone else in Be-Papas was being too mean to the pretty boys - especially Touga, the prettiest boy), but by the end will be nigh-impossible to follow *without* the show because AtR *expects you to have seen the anime*.
Godspeed when it wins anyway. It's gonna be rough.
