No it's not, how does that even make sense ? Emphasis would have been using "twitching" or "pulsing" but bulging mean the part is actually growing in size, that's not ML's dick, that's MC's part growing like a dick would, there's even a panel where the real dick is missing.
You cannot convince me a human draw this shit.
Why you gotta be such an ass when you're the one asking a question? Tf is that shitty attitude, mate. You can think whatever you want but at least use some reading comprehension. It's bulging in that panel because ML's dick went in and it's pressing on it. No it's not good anatomy, it's shitty made-up yaoi anatomy and it would never do that irl but guess what? porn is full of shit like that
At the end of the day: don't like don't read
I literally just matched your energy after your previous message
Going back to it, a lot of yaoi has shitty and weird anatomy especially when it comes to the bottom cos they keep feminizing their bodies in all sort of weird ways. Might be cos a lot of these artists aren't (gay) men and Japanese porn is censored so sometimes they be just winging shit
I'll chalk it as misread energy due to lack of intonation. Moving on.
Like I said we aren't talking about a self-lubricating butthole that mix butthole and vagina for various dumb reasons or perpetually hard dicks for the convenience of keeping the scene going. We're talking about ignoring a whole ass bone (Pun intended). Like, take your hand, put it down there and just feel your own bone that begin above the clit and stop beneath it before the vagina. This part of the bone is called the pubic symphysis. It's not feminization, we all have those pubic bones there. There's no soft area like the belly between the asshole and the genitals, it's all bone and tendons.
So we can find as many excuses as we want, this area bulging isn't human anatomy, that's fish anatomy. (And not even every fishes)

Is this AI ? It feels like an AI confused a dick getting hard through the clothes with his skin ? Why the hell would the part between the dick and butthole "bulge" ? What kind of alien sex am I watching ?