This has nothing to do with Cave Story. Nigoro, if you haven't heard is a Japanese developer based in Tokyo. I had the chance to hang out with them while visiting Japan for TGS. It's time to take a break from working on Cave Story so I'm playing a game by Nigoro. Rose and Camellia is one of their free flash games. It's simply hilarious and not necessarily safe for work.
Rose and Camellia also have nothing to do with this Basshunter video, but he's from Sweden just like Nicklas.