According to the official website, an unaired episode of Chuunibyou demo Koi ga Shitai!
was announced to be released on the seventh volume of the Blu-ray & DVD. The release date is June 19, 2013.
Source: Chu2 Byo official website
Chuunibyou Demo Koi ga Shitai!: Kirameki no... Slapstick Noel