Kojima first got his start in the animation business in the 1980s, where he worked primarily project-to-project for a number of different companies, including Knack Productions and Tatsunoko Production. During this time, his involvement was in television products mostly as an episode director. After joining Madhouse in the 1990s, he took part in dozens of productions as an animator, as well as helming several TV series, two movies, a theatrical short, and a TV special. He has since left the studio and joined Kinema Citrus in 2011.

Since coming to work for Madhouse, Kojima has been primarily a drama director, and one who specializes in lengthy series. He has directed two adaptations of Naoki Urasawa's manga, Master Keaton and Monster, both of which have received critical acclaim. His first full-length theatrical film, Piano no Mori, was released in Japan on July 21, 2007.

Director edit

• Azuki-chan (1995–1998) — Series Director, Storyboard, Animation Director
• DNA Sights 999.9 (1998) — Director, Storyboard
• Master Keaton (1998–1999) — Series Director, Storyboard (eps. 1–2, 4, 13), Episode Director (eps. 2, 13)
• Leave it to Kero! Theatrical Version (2000) — Director
• Magical Shopping Arcade Abenobashi (2002) — Series Director, Storyboard (eps. 2, 10, 12), Episode Director (ep. 2)
• Hanada Shōnen Shi (2002) — Director
• Monster (2004–2005) — Director, Storyboard (eps. 1–2, 6, 8, 38, 67, 73-74), Episode Director (eps. 1, 73), Key Animation
• A Spirit of the Sun (2006) — Director, Storyboard
• Piano no Mori (2007) — Director, Storyboard
• The Tibetan Dog (2011) — Director, Storyboard
• Busou Shinki: Moon Angel (2011-2012) — Director, Storyboard, Episode Director
• Bottom Biting Bug (2012-2013) — Director (eps. 1-52)
• Black Bullet (2014) — Director, Key Animation (ep. 13)
• Made in Abyss (2017–2022) — Director, Storyboard (eps. 1–3, 5, 8-10, 12-13), Episode Director (ep. 12)

Other edit

• Cybot Robotchi (1982–1983) — Episode Director
• Okawari-Boy Starzan S (1984) — Storyboard, Episode Director
• Aru Kararu no Isan OVA (1993) — Storyboard
• Cardcaptor Sakura (1998) — Storyboard (ep. 2)
• Reign: The Conqueror (1999) — Storyboard
• Sakura Wars (2000) — Animation Director
• Shingu: Secret of the Stellar Wars (2001) — Storyboard
• Space Pirate Captain Herlock The Endless Odyssey OVA (2002) — Storyboard (eps. 7-8)
• Trava: Fist Planet OVA (2003) — In-Between Animation
• Texhnolyze (2003) — Storyboard (ep. 7)
• Gungrave (2003–2004) — Key Animation (eps. 1–2, 8, 18)
• Gunslinger Girl (2003–2004) — Storyboard (ep. 3)
• Gokusen (2004) — Storyboard
• Samurai Champloo (2004–2005) — Key Animation (eps. 5, 22)
• Trinity Blood (2005) — Storyboard
• Black Lagoon (2006) — Key Animation

• Masayuki Kojima at Anime News Network's encyclopedia
• Masayuki Kojima at IMDb