Sankarea: Wagahai mo... Zombie de Aru...
English name: Sankarea: I, Too, Am... A Zombie...
Genres: Comedy, Horror, Romance, Supernatural, Ecchi
Type: Special, Episodes: 1
Aired: Nov 30, 2012
Studio: Studio Deen
Source: Manga
Rating: R+ - Mild Nudity
Synopsis:
Extra episode included on BD/DVD vol. 6; effectively episode 13. 

Despite their decaying bodies, Rea’s zombie power comes in handy both at school and at home, and Babu gets interested in another cat—although this particular feline is one of the living.

(Source: FUNimation)