Mitsutoshi made his debut in 1996 in Weekly Shounen Jump and received a Akatsuka Award for best new humorous manga cartoonist writer for his series Seikimatsu Leader den Takeshi!(1997–2002, 24 volumes), for which he also won the 2001 Shogakukan Manga Award for children's manga.
In 2002, Mitsutoshi was arrested and convicted of violating child prostitution laws, including paying a 16-year-old girl ¥80,000 to have sex. As a result of the arrest, Seikimatsu Leader Den Takeshi! was cancelled by Weekly Shounen Jump, but the sentence was suspended after 2 days and he was free to go.
In 2004, Mitsutoshi returned to manga with a sports/comedy manga, Ring, which continued for 3 volumes (24 chapters) in Super Jump magazine.
Mitsutoshi's next series was Toriko, which was serialized in Weekly Shounen Jump from 2008 to 2016. It was nominated for the 2nd Manga Taisho Award in 2009 but did not win.