I just heard about this recently, not surprisingly to see why, and finished it all in less than one night. I was hoping for something entertaining related to the yakuza but the closest thing to that would be the rivalry between clans...and everything else is just out the window with said clans being just high school students killing each other nonsensically with semi-explained supernatural powers in an alternate history in which they end up having to change into one that makes more sense in our own reality. Well that was quite the run-on sentence, but that pretty much sums it all up.

I found it to be quite inconsistent, switching genres between high school slice-of-life, to gory Battle Royale-like action, to X-rated sex scenes, then to action-drama at the climax, and bits of romantic comedy thrown in here and there. The story (what if the bomb was never dropped on Hiroshima because it was stopped by super powers to control time and space) in itself was interesting, but the delivery wasn't so much (said super powers controlled by high school students in clans instead of clubs, killing each other for no other reason except rivalry, and to get a good grade (they're marked by the educators of their death toll and survival rate).

The characters had a lot of potential to shine because they were interesting and likable, but not a whole lot of development considering the length of the manga.

At least the art was good and tasteful. Although it might not sit to well with other people that have weak stomachs. Or tired eyes because there is just so much crammed onto a page that you might not know where to look first or what your even looking at.