This poster was drawn in 5 stages (four corners, one top image) in pencil, inked by hand, then coloured on a computer. The backgrounds of each corner were sketched, then drawn and painted digitally. Each corner took roughly 4-5 hours to drawn, ink, and colour.
The poster is for sale on Redbubbled, though I dunno why you'd be interested in that: https://www.redbubble.com/people/zuperbuuworks/works/33141781-jinimaru-folklore-poster-set-1?asc=u&p=poster

The poster covers the first four volumes of Jinimaru Folklore, and has the main character from the first major volume of the Specimen G-13 Series.

Vol 1: http://www.lulu.com/shop/thomas-edwards/jinimaru-folklore-volume-1-origins/ebook/product-23764324.html
Vol 2: http://www.lulu.com/shop/thomas-edwards/jinimaru-folklore-volume-2-koru-and-koura/ebook/product-23764331.html
Vol 3: (soon)
Vol 4: (soon)
Specimen G-13: (Soon)