
wait WHAAAAAAT-
ok so I looked it up and an asshole (of either gender) can secrete a watery liquid from its mucus membranes to make the gut slippery (for digestion and uh "other" reasons). Not related to arousal for most ppl though (it has not been scientifically proven at least, it's more of a word of mouth theory that for some ppl it can happen), and it is generally not enough to do anal for the love of god ppl (not to you @Nf13 just in general)!! Some ppl produce more than others, and it can also be related to what you've eaten sometimes.
I've put my fingers up ppl's bums enough to testify on this also lol, it does feel a bit wet down there usually but without lube ure asking for trouble and if you find liquids of suspicious amounts your nails will come out brown underneath hahahaha. How fun that is depends on a person's turn ons tho I guess and how much u wanna play into "feminizing" the partner you are fingering as part of the act.
not to ruin this sex scene for y'all but while re-reading (cause it was good smut >_>) I realized Yoo-Il says that Soohyun is wet... Unless some sci-fi bioengineering happened to make the uke's asshole self lubricate or I missed the lubing part GIRL THATS POOP JUICE I AM SORRY OK