This is one of the Artist's Proofs sold by Stan directly to his fans at conventions.
"This is number AC of 500 copies of the hardcover edition ... each of which has been individually signed, numbered, and illustrated by Stan Sakai." It has a bound-in limitation page with a 4 inch square where Stan has drawn a full scene with Usagi and a tokage in a grassy field "Eep!"
An Artist's Proof numbered AC would be the 29th Artist's Proof. Also known as a Hors Commerce (or "HC") copy in France.
Volume 9 collects issues 7-14 of the Mirage comic book series Usagi Yojimbo Volume Two, including a cover gallery. Introduction by James Robinson.
From the publisher:
Continuing our collections of the out-of-print issues originally published by Mirage, Stan Sakai's rabbit ronin continues his journey through a lawless land. Usagi meets a mysterious assassin disguised as a priest, encounters dishonest gamblers, and comes to the aid of the unfortunate. This limited edition hardcover includes a signed and numbered illustration, only available with this book.