[Krang]

Yep, that's Classic 4 (Concertare) EX, and it's one of the more challenging songs in Pop'n Music. Throughout the series, there are songs that range from very easy to even more difficult than that one. It's a really fun series, though, especially if you can play in the arcade (not very likely due to its rarity outside of Japan) or using an arcade style controller at home.