Anyway, now that the site's gone hot again...
As I discussed with you over Spacebattles PM...
I could go with a Weather Pattern manipulation device.
Not precise weather control, but manipulation of general, large scale weather patterns. Something that would be useful if used correctly to do things like manipulate a monsoon season, or control the rate and intensity of cold fronts. Nothing that gives you the ability to spawn tornados, or any kind of Instant deadly weapon, but in the wrong hands, could result in the most horrifying series of perfect storms, and hurricane seasons the likes of which make you WISH they had it as a precise device.
Essentially, the way I would imagine it, is that out of control, produces Superstorms like that of 'The Day After Tomarrow' where pretty much all of modern society is royally shafted. For story purposes, that makes a good superweapon out of what is supposed to be some tool.
I've been reviewing a few Japanese mythical beasts... and I think America could do well to know monsters from other cultures. Vampires, Werewolves, and all that have been done to DEATH.
Let's see how people handle a Kappa, a Kitsune, and oni...
http://en.wikipedia.org/wiki/Kappa_(folklore)
http://en.wikipedia.org/wiki/Kitsunehttp://en.wikipedia.org/wiki/Oni_(folklore)
So I would work it like thus.
Our villains are broken up into casts... (Though, taking a time out here to point out HALO, it's not as severe as that.)
Kitsune are the leaders. Competent, cunning, and able to disguise themselves.
Physically the closest to human's in terms of reletive strength, but carry the most potent natural magic.
Kappa, too polite to take the leadership role away, often exploited, and they know it. Usually, they act as a front because while Kitsune are cunning, Kappa are polite to a fault and can be the perfect cover for any operation. They look human in public, though for the love of money, people can't figure out why certain people just refuse to take their hats off. In a fight, they're damn hard to hurt unless you know what you're against and what to go after.
Oni... (Ogres, Demons, Trolls... Pick your favorite) ... The dumb backbone of the group. Well, dumb reletive to Kitsune. But not Too Dumb To Live. These guys are tough, and where Kitsune are strategic thinkers, Oni are tactical thinkers. In a sense, they're like Marines. They like to get in, smash the F*CK out of enemies, and live to do it again. Getting killed on head-on rampages is rather detrimental to that.
For motivation, it could just be ages old disgruntled anger at the fact that humans have all but run the globe over, forcing them from what was 'rightfully' their homes. Revenge is a recognizable motivation and driving force of irrationally elaborate schemes, rather than base greed. And to tie in the Magical Girls... it was Sun Tsu who set things down the path to irrecoverable imbalance when he set his honor guard up... and taught humans on earth how to REALLY make war.
It's taken Kitsunes a lot of undercover work to get to a point where they have an operation... but the first task of the operation is to eliminate the most dangerous single combat opponents... the descendants of the Valkyrie... 'Magical Girls'.
A few things I could go for is at least one Kappa defecting to the Good Guys. These guys are polite. A lot of them think that trying to destroy humans or at least destroy their society and cripple their race is a poor option. But see defecting as extremely impolite to their current party... The defector could be the most impolite Kappa ever known. (Not rude mind you, but a black sheep of Kappa who manages to find a way around natural Kappa nature by talking himself into things by loopholing his way through the routines. (Example: Japanese custom is to bow..., which for a kappa is a weakness as it makes them spill the water on their head. Instead, this Kappa would worm his way into using salutes or handshakes to avoid bowing.)
Also... one Oni who will take a liking to WH 40k, and is often jamming on an electric guitar citing "I iz made 4 rokkin!" (Making an Ork Easter Egg without making a direct refference.)
Keep the thoughts flowing.