Good "J-Core" artists like DJ Technorch, Blasterhead, and USAO, not this DJ Sharpnel crap.
Mass of the Fermenting Dregs are amazing and as long as they even release so much as an album yearly, they will be as much of a household name as Number Girl in the "indie" Japanese rock world.
µ-Ziq is more highly underrated and thrown under the bus than ignored. I blame the erratic quality of his album releases (ROYAL ASTRONOMY SUX).
Swans is still kind of popular among some groups but for the most part ignored by "casual" music listeners.
Vivian Girls are still technically cult status, but they're becoming more popular.