I do like this! It's a jolly little tune, performed by Miku Hatsune (the Vocaloid) very nicely. The original, performed by the Finnish vocal group Loituma, can be found in an embedded video on this page containing the original lyrics. Theirs was good; this is better!
The title is often spelt as Levan Polka, which I think derives from the Finnish pronunciation of the name Ieva (whose tale is featured in the lyrics) sounding a bit like an 'l' at the start.
Incidentally, this seems to be the song most closely associated with the "Welsh onion twirling" that has been around in anime for a while, and explains the 'leek'-shaped (as often described: it's actually a spring onion) glowsticks you might have noticed at the Vocaloid concert in Sapporo that I posted here recently. There are several videos on-line showing this twirling in action, which I mention just in case you wish to pursue this further (I've already looked: it really isn't all that exciting!)
This song works really well for Miku, especially in this setting and if anything even better once the scenery blooms nearly half way through. Yo!