SUEZEN is the professional alias of Fumio Iida, a Japanese animator, manga artist, illustrator, and character designer born in Tokyo. He is a male creator who began his career in the animation industry after graduating from private Meguro High School and joining the Tatsunoko Animation Technology Institute, where he studied under Sadao Miyamoto. His professional name, SUEZEN, is thought by some to derive from a Japanese proverb, but he has suggested in an interview that it comes from an idea meaning that even if one cannot achieve the best, one can still aim for the last good.

Before becoming known for his manga, SUEZEN established himself as a key animator and key art provider, often working under his real name, Fumio Iida. His early animation credits include major productions such as the television series Dash Kappei (1981) and Super Dimension Fortress Macross (1982), where he served as a key animator. He gained significant recognition for his work as an animation director and production designer on the landmark film Royal Space Force: The Wings of Honneamise (1987). Throughout his animation career, he also contributed to other notable projects, including the original video animation Gunbuster (1988), the film Roujin Z (1991), and the anime series The Prince of Tennis.

While continuing to work in animation, SUEZEN pursued a parallel career in manga. He made his manga debut in 1988 with a work titled Mystery Light. He rose to prominence as an original creator in 1992 when he served as the character designer for the anime series Yadamon, also known as "Little Witch Yadamon". That same year, he began serializing a manga adaptation of Yadamon in the monthly magazine Animage, which was later published as two collected volumes. This project established his reputation in both the animation and comics fields.

Following the success of Yadamon, SUEZEN continued to create original manga series. One of his significant works is Marinkara (also known as "Color of Mermaid" or "七彩美人鱼"), a story about a mermaid aspiring to be a designer, which was serialized in Shonen Ace magazine and collected into five volumes. He also authored original manga such as Percolation and Shinseikatsu -Neo Life-. In addition to his own creations, he has adapted other works into manga, including Kaze Makase Tsukikage Ran (based on an original story by director Tetsuro Amino) and a version of the Dead Space video game.

SUEZEN's artistic identity is characterized by a flowing, smooth drawing style that incorporates techniques from shoujo (girls') manga. His characters are typically drawn with distinctive round, upturned eyes. He often uses a female character with these traits as a self-portrait in the afterwords of his manga, which has led some fans to mistakenly believe the creator is female. He is also known to have used the pen name AGEZEN for his dōjin (self-published) works.

Throughout his career, SUEZEN has balanced his work as a manga creator with ongoing contributions to the animation industry as a character designer, key animator, and director. He has maintained long-term relationships with studios such as Gainax, contributing to series like Tengen Toppa Gurren Lagann and the Rebuild of Evangelion films. He has also worked as a character designer for video games, including Shining Force II. As of 2024, he remains active in the industry, most recently credited as the character designer for the television anime Ballpark de Tsukamaete!. His significance lies in his rare status as a creator who has made influential contributions both as a leading animator on landmark projects and as the original author of several long-running manga series.