PuriGorota: Uchuu no Yuujou Daibouken

Original: プリごろ太 宇宙の友情大冒険

First appeared in Nodame Cantabile manga as a fictional anime series. Later, in episode 4 of the live-action TV drama it appeared as a theatrical movie. Finally, the "movie" was completed and included in Nodame Cantabile anime DVD as an extra feature. (Source: Anime News Network)