Hand waving goes a long way as I'm sure you know from your travels. And Osaka is a big city, so there's probably more English spoken there than somewhere like here, where you only ever really hear it from exchange students or people who study it at the university. Sure you'll be fine.
Just had a thought: if you've been everywhere in the region, did you go to North Korea? Have always had a sort of perverse interest in taking a trip there.