In 2005, he joined Vega Entertainment, an animation production company, as a Inbetweening
worker and later a director. After working there, he became a freelance director and worked on Pocket Monsters Best Wishes. He made his directorial debut at the age of 28, taking over from Norihiko Sudo, the previous director of Pocket Monsters XY. As an Animation Director and Movie Director, he is best known for Pokémon the Movie Coco, Pokémon the Movie Everyone's Story and the main anime series XY and XY&Z.
On his official Twitter @tetsuo_yajima
, he will often comment about current Pokémon anime events.