Tsukuyomi: Moon Phase Special  

Onii-sama, Yurayura Kirakira Donburako Korette, Naan Da?, Up and Down, in the Sun, Floating Away? What Is It?, 月詠 -MOON PHASE- おにいさま

Omake Special from the final DVD volume. The Special storyline has very little to do with the original series outside of having some of the same characters, and has a completely different storyline which does not fit into anything which came before it.(Source: AniDB)