United Game Artists (UGA) was a subsidiary of Sega headquartered in Shibuya, Tokyo, Japan. It was founded by Tetsuya Mizuguchi, a video game developer who had experience with Sega's AM3 division. After separating with Kenji Sasaki to form AM Annex, Mizuguchi left Sasaki's team to form another division. This studio would later be known as Sega Consumer Development 4 (CS4) and Research and Development #9 while a department of Sega, before becoming UGA as a wholly owned subsidiary of Sega.

Tetsuya Mizuguchi is a Japanese video game designer, producer, and businessman. Along with ex-Sega developers he is one of the co-founders of the video game development firm Q Entertainment. He formerly worked for Sega as a producer in their Sega AM3 'arcade machines' team, developing games like Sega Rally Championship and Sega Touring Car Championship, before moving on to become the head of Sega's United Game Artists division, the team responsible for Rez and Space Channel 5. Mizuguchi is better known for creating video games that incorporate interactive synesthesia into his game design, regardless of genre, evidenced by Rez, Lumines, Child of Eden, and Tetris Effect.