D.Gray-man, Volume 14 (D.Gray-man #129-138)

Cross Marian is about to finish off Tyki Mikk when the Millennium Earl barges in, spreading chaos and destruction in every direction! The Earl's plan to build a new Ark using data downloads from the old one seems unstoppable, until Allen encounters a strange apparition that tells him to play the piano. Allen would be more than happy to oblige, but there's one slight problem - he never learned how!