Shun made his TV debut in NHK's drama Hachidai Shogun Yoshimune in 1995. In 1998, by playing the bullied and abused child Noboru Yoshikawa in the drama Great Teacher Onizuka, Shun started to be recognized by the public. His act in that drama attracted the attention, and brought him bigger roles. In 2000, he played a deaf person in Summer Snow. Two years later, he starred in the popular drama Gokusen, in which he played a part of a bully, rather than the bullied as he did in Great Teacher Onizuka. In 2005, Shun lent his voice as a voice actor in Fullmetal Alchemist the Movie: Conqueror of Shamballa together with his brother Ryo Oguri.