Tee-hoo, tee-hee, time for another dupe trick from me!
Are you running low on servants? don't want to deal with the grind of getting more for my witch bottle glitch? Well have i got just the thing for you! You do need access to the kitsune manor, but you need to beat the game to dupe witch bottles anyway so :shrug:
Talk to the merchant. go to requests. If the request is for a hero's crest, (and if you have 3, i'm not sure if other values work but 3 is what I had), then simply press shift and then enter 11 times. this completes the dialog. repeat. while the crests ARE removed, even when you have zero, and even on other days, you can still do this. When you feel you have enough pipe foxes, simply do not repeat the dialog. There is no restriction on how fast you may do this as long as your keypresses are accurate.
PS: Not sure if the witch bottle glitch has a fix but i don't itch to check so that's the sitch