Man, I like how Itsuki is such a bro to Hayato. This guy must have met a few isekai'd people there and probably has seen his fair share of the shitty ones. Itsuki being an older friend and being a functional adult is a godsend for him.
Why not just give them the damn elixir and be done with it???? Why go out of your way to travel to the capital to buy an overpriced maybe fake elixir?????