Hi,
I'm looking for a manga I read some time ago;
it was about a small town (or maybe just a district of a bigger town) where people get numbers tattoos on their bodies overnight; at the beginninig we follow high school students, so first we think it's only the school (they have a medical visit during which they discover it, I think). The tattoos seem to give powers (like fire, invoking a weapon, or the usual supernatural stuff), but on the other hand if a tattooed person touches the ground with both bare hands (or just one?), they die. And nobody's got a clue what's going on: no big bad guys so far, no visible evil scheme.
Oh, by the way, the army thought it might be dangerous so it locked them all inside, building a big wall around town and shooting anybody who tries to leave.
Then there's someone (a journalist maybe?) who wants to get inside, and he has to cross a river (not to be seen by the military guys; there's a kind of barrage that marks the limit of the town; an insider who seems to know more than he should about this mess helps him) and there he sees the fish has mutated and turned really dangerous.
And that's all I remember.
Rings a bell, anyone?

Definitely Wizards Nation

Wow, what a fast answer!

Thanks a lot, that's it!