Keroppi's Grand Adventure (English FanSub)

"We're the center right now!
Cause we're a rock group, yeah yeah!"

Plot: After a hidden message in a golden crown gets Keroppi wondering what a belly button is, he seeks out Pokopon in his home village to find the answer, only to come across his girlfriend (sister in the English dub) Hana-chan who tells him Pokopon's belly button was stolen during a storm. Thus, Keroppi and his friends Teru Teru and Den Den set out on a grand adventure for Thunder Mountain to get it back!

Also known as Kero Kero Keroppi no Dai Bouken (けろけろけろっぴの大冒険), or Keroppi in the Big Adventure, along with a few other title variants.

This OVA is based on a comic series that was featured in the Strawberry News of the same name and featured similar events, only instead Keroppi seeks the answer about belly buttons from a wise Uncle Scarecrow and ends up trading the golden crown with the thunder god in order to get the scarecrow back his bellybutton. By the end of the comic though, Keroppi is still left wondering what a bellybutton really is!