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.

Sega AM Research & Development No. 3, known as Hitmaker Co., Ltd. from 2000 to 2004, is a defunct division of Sega, a Japanese video game company. Established by 1993, AM3 was managed by Hisao Oguchi and developed a number of arcade games for Sega. Series introduced by AM3 include Virtual On, Sega Rally, Crazy Taxi, and Virtua Tennis. AM3's main focus was on arcade games until the release of the Dreamcast. Additionally, developers Tetsuya Mizuguchi and Kenji Sasaki developed Sega Rally Championship with AM3 before departing to form AM Annex, which later split into Sega AM9 and Sega AM5.