Matsuri no Tatsujin Winchan no Natsu Matsuri - Winchan Ondo...

[Myrkul]

I am unable to romanize the last part of the title (～お祭り広場は小さな宇宙～)... Otsumari something ..

I have no concrete source, but it seems like the sountrack (like some other Yamasa albums) was available on Yamasa online shop, this one was around 700 yens.

[dancey]

This is an educated guess, but maybe: "~Omatsuri hiroba wa chisana uchuu~"

*edit*

Wait, it's already romanized as that ... ?!

[Myrkul]

Yep, Chz did it, thanks to him.