As a teenager Yamashita was influenced by the works of Yoshiyuki Tomino and Tomonori Kogawa, and was inspired to become an animator.
After graduating from Kurashiki Minami High School, he moved to Tokyo to become an animator and joined Bevore. After Bevore's dissolution, he joined Atelier Giga, and from there he joined Project Team Muu. There he was jointly in charge of the character designs, animation direction and storyboards for Giant Robo the Animation: The Day the Earth Stood Still. The production took nearly 10 years, during which Yamashita gave it his all. After the production was over he started losing his motivation for animation. Though, it sparked again, after having met Norio Matsumoto and Tomohiro Hirata on the opening animation for a video game called, Gensou Suikogaiden.
In 2001, Yamashita worked as a key animator on Spirited Away, a Studio Ghibli feature film. There he was in charge of multiple scenes, most notably Chihiro and Haru's free fall at the end of the movie. This earned him high high praise from Hayao Miyazaki, and he was thus selected as one of the animation director's for How's Moving Castle. Since then he has served as an animation director on most of Ghibli's movies.
In 2018, Yamashita directed "The Invisible Man," a short film part of the anthology collection Modest Heroes, produced by Studio Ponoc. The film won the Newcomer's Award in the Animation Division at the 22nd Japan Media Arts Festival
Married to Miho Shimogasa.
