Attempting to gather all these over-the-top Japanese splatter/gore films into one big bloody list. It's a personal favorite niche genre, but I'm still not entirely sure where exactly to draw the line. Noboru Iguchi, Ryûhei Kitamura, Yoshihiro Nishimura, and Yudai Yamaguchi seem to be at the forefront of the niche and/or pioneers of it. But none are limited strictly to it. So there's mainly a difficult-to-define 'quality' about them that fits them into this list.
I tend toward inclusivity with my lists, so if something's on the fence, I'll probably just toss it in anyway. Generally speaking however, I'm going to steer clear of the Guinea Pig series and similar older torture-horror movies, since it's a different breed.
As always, suggestions welcomed.