I actually fully disagree with the idea that it’s better to sell out than to have extra and I’ve never heard that logic before to be honest?
Though I mainly avoid anime conventions I do several every year and it’s always, always preferable to have leftover. Taking stuff to cons and having space for stuff is always hard but that’s part of the battle. You just take your leftovers to sell online or at your next con. It’s always better to be over prepared because by only bringing a handful of prints you’re basically putting a hard cap on the amount of money you’ll be able to make. Sure, at your first few conventions it’ll feel kind of nice to fully clear inventory but the more cons you do the more you’ll realize it’s basically throwing money out the window.
Don’t get into the bad habit of under-preparing. Selling out of a print you only brought five of doesn’t mean a lot in the long run and might be severely limiting because the truth is you will never know exactly how much you’ll sell at any given con.
In my early days of doing cons I would bring maybe 10-15 copies of my comic and end up feeling really good when I sold out but I could’ve been selling a lot more and actually making a decent profit without realizing what the actual demand was at the time. It also turns out it LOOKS better to not have a bunch of sold out stuff on the table when you look at how a lot of professionals and companies operate tables. I’ve learned the hard way that having a sparse table just makes you look underprepared and unprofessional.
Granted, I don’t know your skill level, what type of cons you’re doing, how the attendance is, and willingness of attendees to support the work. But most people can’t predict that even after doing hundreds of cons.