I expected that at least one of the many active volcanoes on caldera-ridden Kyushu would land on the New Decade Volcano Program at Volcano Café, though I wasn’t sure which it would be: Aira, Aso, or one of the less-publicized ones. This weekend NDVP #4 turned out to be the Aso Caldera and, yes, it is potentially extremely nightmarish.
There are three more to go. From the comments to the Café post:
BillG: So this is #4…. I can’t imagine there are three worse scenarios..
Henrik: Trust me Bill, there are. One marginally more so, one decidedly worse and the final one so utterly mind-blowing that eventually Hollywood will make a blockbuster movie of it.
I would guess that one of those three is either Campi Flegrei or Vesuvius; the other two, I have no idea. I note that five of the volcanoes announced in the NDVP so far are in Asia and none in South America, and there are a lot of interesting mountains and lakes in Central and South America.
You can watch the Nakadake crater at Aso at the JMA site. The link to the camera is highlighted here (“Aso grass Chisato,” according to Giggle Translate):

You can usually see a plume of steam and gasses when the weather is clear, and occasionally some incandescence.
Update (9/13/15): Aso had a bit of a cough today (or tomorrow, depending on which side of the International Date Line you’re on).
Update II (9/18/15): … and coming in at #3, it’s Campi Flegrei.