The story
1980s
Touch (1985–1987) (production assistance; animated by Group TAC)
High School! Kimengumi (1985–1987) (production assistance; animated by Studio Comet)
The Three Musketeers Anime (1987–1989) (animation cooperation with Sei Young Animation)
Kiteretsu Daihyakka (1988–1996)
Gaki Deka (1989–1990)
Miracle Giants Dome-kun (1989–1990)
1990s
Tanken Goblin Tou (1990–1991)
RPG Densetsu Hepoi (1990–1991)
Read the full text
Genji Tsūshin Agedama (1991–1992)
Chikyū SOS Soreike Kororin (1992–1993)
Hime-chan's Ribbon (1992–1993)
Akazukin Chacha (1994–1995)
Nurse Angel Ririka SOS (1995–1996)
Rurouni Kenshin (1996–1997) (first 66 episodes; later animated by Studio Deen)
Kodocha (1996–1998)
Kochira Katsushika-ku Kameari Kōen-mae Hashutsujo (regular broadcast: 1996–2004; special broadcast: 2005–2008; last special episode: 2016)
Anime television de Hakken! Tamagotchi (1997–1998)
Initial D: First Stage (1998) (animation cooperation with Studio Comet)
Ojarumaru (1998–present)
2000s
Transformers: Car Robots (2000)
Yu-Gi-Oh! Duel Monsters (2000–2004)
Forza Hidemaru (2002)
Legendz Yomigaeru Ryūō Densetsu (2004–2005)
Morizo to Kikkoro (2004–2005)
Yu-Gi-Oh! GX (2004–2008)
Animal Yokocho (2005–2006)
Eyeshield 21 (2005–2008)
Hataraki Man (2006)
Yu-Gi-Oh! 5D's (2008–2011)
Mainichi Kaasan (2009–2011, first 96 episodes; later animated by TYO Animations)
2010s
Yu-Gi-Oh! Zexal (2011–2014)
Yu-Gi-Oh! Arc-V (2014–2017)
Yu-Gi-Oh! VRAINS (2017–2019)
Bakutsuri Bar Hunter (2018–2019) (animation cooperation with Toei Animation)
2020s
Fushigi Dagashiya Zenitendō (2022–2025) (animation cooperation with Toei Animation; episode 53 onwards)
Me & Roboco (2022–2023)
Kagaku Manga Survival (2024)
Shin Kochira Katsushika-ku Kameari Kōen Mae Hashutsujo (2027)
Original video animations
Prefectural Earth Defense Force (1986)
Mugen Shinshi Bōken Katsugeki-hen (1987)
Maps: Densetsu no Samayoeru Seijintachi (1987)
TWD Express: Rolling Takeoff (1987)
To-y (1987)
One Pound Gospel (1988)
Fujiko F. Fujio no SF Tanpen Theater (1990–1991) (episodes 1–2, 5–6, 9–10)
From Wikipedia’s article on Gallop (studio), shared under CC BY-SA 4.0.4