They will work. There are no Region codes on PS3 games.
However there are a few things to consider before you buy. I imagine you can save some money buing from Japan since you ask.
Some games have online play locked for s specific region. So if you buy a Japanese game you may only be able to compete online with Asian people, also if you buy a game from Japan, in the case of expansions or downloadebel content, you have to buy from same region as the main game, or it will not work.
Last but not least if you are using and analog signal between you PS3 and you Screen there are some games made for NTSC that may appear in only black and white , or other odd stuff if you are playing them on a PAL Screen. This is nothing to worry about if you use a digital signal ( HDMI /DVI)
