is a Japanese pop music band. D-51 is group consisting of two men, Yu and Yasu. They are signed under Pony Canyon label. According to its members, the name D-51 came from Japanese National Railways' D51 steam locomotive class.
In 2005, they had their first big hit with the single No More Cry, which peaked at no. 5 on Oricon charts and became the 13th best selling single of the year, selling 402,034 copies. In 2006, their single "Brand New World" was used as the sixth opening theme for the One Piece anime