Truth be told, if I didn't stop myself I'd easily fill 10 of the 30 with destinations in Japan. It's such a cool place and an amazing pleasure to visit as a tourist, very well developed and getting easier and easier for nearly anyone to get around.
Guitar Hero meets Pokemon meets Duck Hunt - I had to shoot the correct balloon-shaped animals as they appeared and all in time to music! Strangely appealing and you can't help but dance with your pink pistol hahaha
I spent a couple of weeks on an east to west itinerary, exploring Japan in August of 2010, with Osaka pretty much bang in the middle of my trip.
Where the sprawling metropolis of Tokyo is truly awesome to the point of overwhelming, Osaka might be a little more accessible in many respects. It's also renown for its food (my word, you'd be forgiven if you thought I just eat my way around the globe at this point haha).
Cool flashing lights, arcades to delight all ages, there are castles and temples among the multitude of historic sites and a modern aquarium with whale sharks!
Did I mention the food?
Street food: BBQ octopus with tiny, tiny chopsticks (or toothpicks haha) and a Japanese beer. Awesome.