The occasion was some kind of expo at Makuhari Messe in Chiba, attended by people (mostly men from what I've seen) who are very much into costume play and like the world of make-belief.
The expo, "NicoNico Chokaigi 2", is backed by the Ministry of Internal Affairs and Communications, and the Ministry of Economy, Trade and Industry. There are booths by Liberal Democratic Party, Japan Restoration Party, Japan Communist Party, and Democratic Party of Japan as well as Self Defense Force and the US Military stationed in Japan.
So, it's got to be that wonderful government-sponsored idea of "Cool Japan" where they live the make-belief "reality" of manga, anime, and video games. Quite fitting for a country where boys are like baby-faced girls and girls wear extra-large color contact lenses to look like manga heroines.
From Mainichi Shinbun (4/27/2013):
He looks pudgy and tired. Radon inhalation may not be working.
Why should I care any more about a country like this, writing about the nuclear accident and radiation contamination that actually exist, non-stop for over two years?
Why should I care? Because there are people like this who immediately created a fake poster like this. It's a poster of an old movie, and the title is "An Idiot Comes Riding a Tank" (H/T N_mittaka):