It was announced in manga magazine LaLa that readers who send in 1350 yen can get a special DVD for the anime “Natsume Yuujinchou” that would include, among other things like seiyuu cast talk session, an anime with a new original story. It is not known how long this anime will be or whether it will show a complete story or just a teaser trailer.
Source: MyNavi, LaLa
Natsume Yuujinchou LaLa Special on MAL