Ukon
If I had to pick a favorite cosplay at ACen, this would be it. I figured it was very unlikely I would meet anybody who simply knew of the unlicensed mystery series Ayatsuri Sakon, so I was extremely surprised to see a cosplayer portraying its puppet star, Ukon! Sakon's costume was flawless, which isn't surprising; she's the one behind the quintessential Ayatsuri Sakon fan site, Clockwork Voices.
See related photos of Ayatsuri Sakon, Sakon, Ukon