This shikishi ("colored paper") is a reproduction of a painting by Miura that he then signed. It was awared to the highest tiers of the crowdfunding campaign that Hakusensha ran to accompany the Big Berserk Exhibition. Only 20 of them were produced.
That particular illustration first appeared on a telephone card released in 2001. It featured a unique 3-fold stand to display the full image. The painting was also included on the dust jacket of volume 22, which was released on Christmas Eve of 2001 in Japan.