"If you only let specific customers buy such items, it's inevitable other customers will complain."
Not really. It will create a huge demand for it, which means the price will skyrocket.
Characters in trouble. Who's going to show up this time?
"It'll be a pain to apologise if you were to die here!"
That sounds like a less than noble reason to want someone to live.
Even if the clothes can't be pierced, there's a lot of pressure from the jaw. Meaning it's just plain magic.
A little unusual for a Demon King to be bad at lying.
The one thing I love about this manga is that despite the harem tag, MC does not actually "collect" harem materials.
Yeah, there's a fair number of competent, non-evil male characters. That's way too rare.
1) Soft armor like clothe shouldn't protect against crushing damage, as even if the fangs couldn't puncture the guy, the force from the dragon's jaw should have started crushing bones and organs.
Yeah, armour quite often doesn't behave like armour. Like, the breast plate wouldn't shatter like that, but more likely deform and get punctured.