marasy8 - Merry ChristmasRough translation on the title, but I think the song is based on 'We Wish You a Merry Christmas"EDIT: Apparently it's a piano cover of a Japanese song called "Merry Christmas" by an artist called Ninomiya Kazunari.
EDIT: Who is also apparently a singer/actor superstar. Found another song of his I like on Youtube:
https://www.youtube.com/watch?v=PCIg-ntMOkg