This is the “Shinjuku Geijutsu Tengoku” (Shinjuku Artistic Heaven), a great festival held every year in October. There were a lot of interesting acts, but for me, the one that stood out was Noemi and Eugene. They were a stilt walking samurai couple searching for the address Shinjuku Sanchome. Beyond the amazing costumes, I’ve never seen performers that seemed to be having so much fun doing their act. They did all kinds of tricks on their stilts, somersalting, hand-walking, and racing around seemingly awkwardly, but always somehow managing not to trample anyone.
Here’s a video of their performance: http://www.youtube.com/watch?v=DD04wQglYYI
The festival is held on the second Sunday in October in various locations around Shinjuku. Most of the performers are on Shinjuku Dori, the street with Studio Alta on it. The event has a website (Japanese only) at: http://homepage2.nifty.com/shinjuku-pr/.