Yaffle is the stage name of Japanese music producer, composer, and arranger Youki Kojima. He is also one of the founding members of Tokyo Recordings with Nariakira Kobukuro。

He has written or produced tracks for various J-pop artists including 藤井風 (Fujii Kaze), ​iri, SIRUP, Capeson, ​adieu, KO SHIBASAKI, Charisma.com and also worked on Japanese film scores and music for adverts.

He started taking piano lessons when he was six years old.

When he entered Aoyama Gakuin Senior High School joined their brass band while also worked in the light music club. Besides that, Yaffle also performs and direct the orchestra and recording the band.

He graduated from high school in 2010 and entered Kunitachi College of Music. Yaffle later started his career as a composer and arranger at the end of 2010.