The potion doesn't work on Tirria. If you ask the apothecary about it, she explains the reason. At the moment, the only girl the potion works on is Vera.
Just asking out of sheer curiosity because it suddenly struck me as I read your reply, but I'm asking, and mean no offense: What if you "accidentally" (legit in-universe, but a player's choice IRL) left out the bib boobz potion (TM) and the little loli cowgirl drank it? Would a potion like that be SUPER EFFECTIVE on cowgirls? I'm not asking for Loli content, legit curious. Also, it'd be hilarious if her mom and "sis" got pissed at your character thinking he WAS trying to go for the loli content. LOL cue cowmama going full raging bullmama on your MC ass! XD
(I'm sorry, I like Cathyl from Monmusu, and I've been to rodeo's so, yeah!) ^~^y
If you like this idea, go ahead and use it! Also, it'd be funny if the elf girl saw the cowloli after the accident and got jealous and started whacking you 'angry anime girl style' (TM) shouting "YOU'LL MAKE A LITTLE GIRLS BOOBS BIGGER BUT NOT MINE! YOU JACKASSHOLE!" (Cue angry elven tirade that doesn't translate.)
Dude, come to think of it, you could have a LOT of fun with "Potion accidents"! >;P
If you want to use ANY of these "PA" (TM) ideas, go right ahead dude! My gift to ya!
And again, not asking for LoliContent, I just thought it'd lead to hilarious situations.
Anyways, thanks again for this awesome game, and happy holidays!
(BTW, anyone ever draw the Cow-Chan Clan being visited by MC Santa Clause?)