Of course, "post-hardcore," like most of the "post-" genres, is a very broad, all-encompassing term applied to many different bands. Essentially, it means music derived from hardcore punk, but which takes it much further than the typical genre constraints that hardcore punk has. It can refer to bands as diverse as Coheed & Cambria and The Mars Volta, as well as the various "screamo" bands that have been coming out recently. So when I heard of a post-hardcore band called Asian Kung-fu Generation, I wasn't sure what to expect.

What I found on this trip to the world of Japanese music wasn't as brilliant as Boris or as insane as Acid Mothers Temple, but was instead one of the catchiest, most interesting rock albums I've ever heard. World World World is what Weezer would sound like if they were a Japanese post-hardcore band. Like Weezer, they write straight-to-the-point rock songs, with maybe a little more room for diversion in Asian Kung-fu Generation. Like Weezer, their songs are incredibly catchy. Like Weezer, you're liable to start the album all over again when you finish it. Unlike Weezer, they have some relatively extreme elements to their music, and they didn't start sucking after the 2nd album.
So if you're a fan of great, catchy, interesting independent rock, or of post-hardcore music, you need to check this out. If it's your first experience with vocals sung in Japanese, it might take a bit of acclimation, but the music is good enough that it shouldn't be a large hindrance. Enjoy.