Universal Studios Japan (USJ) is always on the top of my "to go" list whenever I'm visiting Osaka, Japan as I love going to theme parks and playing on the rides. The last few times I went to USJ I would book my theme park tickets prior to travelling to Japan as I didn't want the hassle of queuing up early on the day to purchase the 1 Day Studio Pass and Express 7* pass which are limited for purchase each day.
