Interview with voice actors. // Source: scanned by fencer_x.
This scan has photos from an event held on 7/31/04, in which most of the main cast from Kyoh Kara Maoh! read some lines at a public gathering.

Source: scanned by me, alternative cover scan from Akadot Retail.
Yeah, it looks like this artist was trying pretty hard to imitate the usual artwork style of the anime, but not quite pulling it off...

Cover and doodles by Temari Matsumoto. / Source: scanned by me.
There was a really long Maruma feature and an interview with Temari Matsumoto in this issue. I just got too lazy to scan it, sorry.

Image Cross-Reference (Cover): Asuka May 2006 (textless!).

Source: ripped from the official Maruma website.
A special White Day illustration by Temari Matsumoto, to celebrate White Day on March 14th, 2006.

Image Cross-Reference: Region 2 DVD Shinmakoku demo Valentine?! fan event DVD cover and postcard.

Cover by JPQueen, poster by evercool.
What a lovely illustration. (*drools over the poster*)

Image Cross-Reference: Special Carnival collector's card.

Source: ripped from the official Maruma website.
Special Halloween illustrations by Temari Matsumoto. These wallpapers were available to download for a limited time at maru-ma.com.

Image Cross-Reference: Newtype Romance Fall 2007.

First three images are ripped from Shima x Shima, the last from an unknown source.
Chibi Yuuri, for your pleasure.

Source: ripped from the official Maruma website.
New illustrations by Temari Matsumoto. These wallpapers were available to download for a limited time at maru-ma.com.

Image Cross-References:
01. Novel #14 cover illustration, and Asuka January 2008.
02. Manga volume 04 cover illustration.

Source: Scanned by me.
Hey, it's been a while since Pash did a Maruma poster. Awesome!

Article pages. // Source: Scanned by me.

Image Cross-Reference: Character Designs.

The first image here is scanned by fayetasy. But other than that I either do not know who to credit for these images, or I know neither who to credit nor what the images are actually scans of. If anybody can help me out with some ID, that would be great.

Image Cross-References:
01. 2006 Postcard Calendar (textless!), and a Frontier Works Series IV collectible card.
02. Newtype August and October 2004, and on a shitajiki.