@RennyThe team getting bigger is only a concern for Kazuki, from an in-character and in-world standpoint--the games are balanced toward 4-player co-op because anything higher would be too easy/too hard on the system, but the Monster Hunter Orage manga makes a mention of the in-world explanation being eco-conservation (basically, keeping the hunters from killing every living thing in a hundred mile radius).
It wasn't meant to discourage new players from joining or the cast from growing at all and I hope I didn't make you feel that way. As far as not being familiar with the games, I'm sure anyone here who's played them would be happy to answer any questions, and it's not all that complicated. Hunters use typical RPG items--Potions that heal, or cure status ailments, other items that increase attack power, etc--to hunt Monsters. They then take the scales, claws, hide, etc from the monsters and use them to make their weapons and armor. Progressing through the ranks means hunting bigger monsters and using their parts to build the next set of armor and weapons so you can hunt an even bigger monster. Anything past that is lore or fluff, for the most part, like the fact that the setting is this weird sort of fantasy-cave-man aesthetic and no magic exists (at least not for humans, some of the monsters clearly have something supernatural going on).
Plus, I'm assuming the way these missions are handled right now--Cyrus giving everyone a single task--is just for early set-up, and once the characters have an IC reason to know what they're doing, they'll be able to pick and choose from a number of Quests at the same time so we're not all crowded in the same area.
If that doesn't change your mind though, I hope there's no hard feelings and I didn't make you feel unwelcome.