[Q] "Space Pirate Mito" short

[DocWatson]

Media Blasters included a prequel short, The Peaceful Days of the People of Mito (ミトの面々の平和な日 (http://i113.photobucket.com/albums/n236/doc-watson42/Mitoshort01.jpg), Mito no Menmen no Heiwa na Nichi), on volume 3 (http://www.rightstuf.com/aod/awdvd0315) of the R1 release of Space Pirate Mito (http://fast.animenewsnetwork.com/encyclopedia/anime.php?id=1882). Does anyone know when the short was originally released?

Edit: Added the missing kanji.