Un-Go character designers pako and Yun Kouga released an art book. 
There are some full-colour illustrations here but it’s mostly character designs.
Title: UN-GO pako & Kouga Yun Designworks (UN-GO pako&高河ゆんデザインワークス)
Released: December 2011 by Ichijinsha
Pages: 75
Dedicated to: Un-Go anime series
Download »51.02 MB download mirror: mediafire »