Zzgashi said: This is really good. Why wasn't it in the artbook I got?
It's not from the artbook of Persona 4. Instead, it's from "Soejima Shigenori Artworks 2004-2010," as written in the Source. The book features different artworks by the guy, including some stuff you saw in the P4-artbook as well as other things not featured - like this sketch.
You can buy it here. http://www.amazon.co.jp/dp/4047267473 (I hope this doesn't come off as advertising, but I really want to get this as well, which is why I share it.)