I haven't heard much Japanese metal, but the little that I've heard has been weird and very creative. Defiled may be the craziest of all-- this is some of the most psychotic metal I've heard. Extreme in every way, in its technicality, ridiculously chaotic arrangements, lyrics (although somewhat typical of death metal), and bowel-shaking vocals. The songs are more collections of riffs than real songs, but this is pretty irrelevant. You just have to sit there and let it assault you, without trying to figure it out. They don't really sound like anyone else-- Cryptopsy is probably the closest approximation, although Defiled are a little more "out there." Some of the riffs are incredibly complex. One thing I particularly like is their guitar sound, which has a unique sludgy tone to it. This would probably appeal to most death metal fans-- although a little patience is required.