I caught this at a local theater screening. I love my new theater's ownership!
Usually known for it's gore (or at least what I saw from animated gifs of it online). Riki-oh is simply just a really really silly movie. Violent as hell as the pictures suggest but with the right amount of people in the audience it's enjoyable...
..for about half of it. This movie is so crazy and so ignorant of plot that I felt totally exhausted half way through. When characters turn into monsters and people expand and explode it slowly makes me just feel drained.
For cheese lovers it's a must at least once. For all others, well...it's not forgettable. But I think most will remember watching it then exactly what happened.