The way I see it, it goes like this:
1. Fellatio (licking, sucking, popping etc.)
2. Self-Irrumatio (you can actually see it a lot, there's just no focus on it, and there aren't many actresses in JAV that do this consistently, but in Western porn, there are lots of stars that would blow you away, pun intended, without any force; Sara Vandella comes to mind... Bobbi Starr... lots of 'em)
3. Irrumatio (if the actress is not that good at getting it down herself/not eager etc., then the actor pushes it down himself)
A good example for me since I still watch Western porn sometimes is BlackPayback (I hope it's not blasphemy to mention Western porn so often): with most actresses there, the actor needs to push it down, but with some, the actress is not "forced" much (as far as I remember, Amara Romani is one of them). Hell, some actresses are so good they don't puke even when they need to in the context of the site they're shooting for. That's the art of self-irrumatio
By the way, what's the code for that Shoda Chisato interracial title? I'll start looking for it myself, but just in case I don't find it, I'll ask in advance
P.S. Of course, there are cases when self-irrumatio does not fit the context at all, e.g. oral "r***" etc. But otherwise, the progression is quite logical, I think