Ryuji Masuda is a Japanese CGI animation director and creator, born in 1968 in Kumamoto, Japan. He graduated from the Osaka University of Arts and has also served as a special lecturer at the Kyoto University of Art and Design. His career in animation was influenced by an early interest in film and a pivotal encounter with the computer-generated imagery in Jurassic Park, which led him to study CG at a game company.

Masuda made his debut as a creator with the original anime Popee the Performer, which aired on Kids Station from 2000 to 2003. This series, a three-dimensional computer-generated animation, was produced on a very low budget of 100,000 yen per month and was created with a small team consisting of Masuda, his then-wife Wakako Masuda, and a 3D animator from a video game company. The series is set in a desert circus and is known for its surreal humor, slapstick violence, and lack of dialogue, using only vocal grunts and sound effects to tell its stories. A manga adaptation of Popee the Performer was illustrated by Wakako Masuda.

Following this, Masuda created and directed Ga-Ra-Ku-Ta: Mr. Stain on Junk Alley, which aired on Kids Station in 2003. Like his debut work, this series uses no spoken dialogue and relies on its visuals. It follows the surreal adventures of a vagabond named Mr. Stain and a large feline named Palvan in a junk-filled alley. The show was later broadcast on Cartoon Network's Adult Swim block in Latin America and was released on DVD by Funimation in North America.

Other original works by Masuda include the anime series Funny Pets from 2006 and the manga-like anime OH! Jesus from 2013. He also worked as the CG supervisor on PetitEva: Evangelion@School and served as the chief director on Charady's Daily Joke. Throughout his career, Ryuji Masuda has frequently collaborated with his former spouse, Wakako Masuda, who provided character designs for several of his projects, including Mr. Stain on Junk Alley.