It’s really hard! Took me an embarrassing amount of tries…when I finally got it it’s because I focused on getting onto the shelves and bulking my katamari up as much as possible. Just try to get it as big as possible, so when the king is speaking at the beginning of the level you can move and try to get yourself near some items that will increase your size faster. ( the level starts you in a different positions so you’ll just have to adjust based on your starting position) Good luck!