Kirito's Decide, from his "Symphonic concert dvd".
(...and a song where the orchestra actually brings something to the song, contrary to some other songs on this dvd, especially among the Pierrot songs played... Maaah whatever, you can also see that little Kirito's far more at ease when there are guitars and loud sound around him!)

-If you like this, CD Japan, HMV and other Japanese online shops (who sell official versions, not bootlegs) will be delighted to send you the dvd.-