Japan is better: there's absolutely no tipping, at all. The price you see advertised is the price you pay, and they won't even take your tip. (There are a few exceptions: some American-style cafes have been putting tipping jars at the register; very annoying.) The only caveat is the tax: that's not always counted in the price, so many restaurants show two prices, the pre-tax price and the post-tax price just below it (usually in a smaller font).
The other thing that's MUCH better about Japan vs. Europe is that water is free. In Europe, if you want any drink with your meal at all, you have to ask for it, and if you ask for water, they'll bring a fancy glass bottle of very expensive bottled water. If you ask for tap water they'll give you dirty looks. In Japan, it's more like America: water (tap water, but it's really good) is free, and usually given without asking. Some places put a giant carafe of iced water on your table, which is great during this ridiculously hot summer.
The other thing that's much better about Japan (this isn't really about restaurants, though it does apply to the food court restaurants in malls) is that public bathrooms are free. In Europe, they usually expect you to leave a tip or some kind of fee for the cleaning people. Japan is again more like America: public bathrooms are just that: open to the public, for free. The big differences are that 1) there's a washlet on most toilets, and 2) they're actually clean.