Half a finger is actually where the prostate is located. So it's anatomically accurate, to feel excited at that point
The manhwas where they draw prostate glands high up the ass are not accurate.
I know this because I've done a few rectal exams as a med student
tbh its not even half here its like idk 1/4 buuut as someone who had say gex lmao most of them wont instantly have that reaction specially without lube
My head cannon is the reaction is cuz there is no lube. Shit hurts, going in dry, barely any foreplay :/. Not the sexy horney reaction, but like ouch bruh wth
whats up with authors making bottoms only have half of a finger in and somehow the bottom is already feeling it lmao. Aint even half in how is he already so sensitive