Yeah, that is a little annoying. Luckily when you're out in the world the music is mixed really loud so you don't have to hear "YES SIR!" like 18 times every time you reorder your royal guard. It's kind of drowned out. :lol:
FYI, by first main boss, I mean the Onii King, but before that there's a few mini bosses. Not sure how far you are, but there's a few guardians before the Onii King that give you land but the game stays linear until the Onii King.