Katamari Damacy's soundtrack is a wonderland of chilled, fun and whimsical songs. "Que Sera Sera" is most definitely one such song, which has no doubt contributed to the awards for originality that have been heaped upon this OST.
Sung by Charles Kosei, and evidently with Japanese influences, there's an undeniable Sinatra-like quality to the song's performance.
Like Katamari Damacy's gameplay, "Que Sera Sera" is weird and wonderful. Not only does it make the game itself infinitely more fun to play along to, it stands on its own as a great and easy song to enjoy listening to.
Check out the annotations from YouTube uploader Aubrey McKenzie in the video above - they paint a wonderfully colorful picture, and one that's suitably imaginative for its subject material!