Riichirou Inagaki is a Japanese manga writer born on June 20, 1976, in Tokyo. He began his professional career after working as an animation assistant at a manga and film production company. In October 2001, he debuted as a writer with the one-shot Nandodemo Roku Gatsu Jū San Hi, published in Shogakukan's Big Comic Spirits magazine. He followed this with two more one-shots for the same publication, Square Freeze in November 2001 and Love Love Santa in February 2002.

Inagaki is best known as the original creator behind two major manga franchises, Eyeshield. Stone. In both cases, he is credited with the story and original concept while collaborating with a separate artist. For Eyeshield 21, which was serialized in Weekly Shōnen Jump from July 2002 to June 2009, he worked with illustrator Yusuke Murata. The manga was a significant success, selling over twenty million copies in Japan and receiving a 145-episode anime adaptation that aired from April 2005 to March 2008. After a period of developing several shorter collaborations with various artists, Inagaki began his next major work, Dr. Stone, in Weekly Shōnen Jump in March 2017, partnering with illustrator Boichi. The series concluded in March. Stone manga has been adapted into an extensive anime franchise for which Inagaki receives the original creator credit. The first season, titled Dr. Stone, aired in 2019. It was followed by Dr. Stone: Stone Wars in 2021, the television special Dr. Stone: Ryusui in 2022, Dr. Stone: New World in 2023, and the fourth and final season, Dr. Stone: Science Future, which began airing in 2025. Following the conclusion of Dr. Stone, Inagaki began serializing a new manga, Trillion Game, in Big Comic Superior in December 2020, once again in collaboration with artist Ryoichi Ikegami.

Inagaki's work is characterized by a focus on ambitious protagonists who rely on intellect, strategy, and specialized knowledge. For Dr. Stone, he has stated that he wanted to create a shonen protagonist who was defined by his intelligence and scientific thinking rather than physical strength. He has also mentioned his personal fascination with science as a child as a major influence for the series. In developing the story, he conducted research into scientific accuracy with the help of a consultant.

Within the manga industry, Inagaki is recognized as a significant figure. In 2006, he was selected alongside Akira Toriyama and Eiichiro Oda to serve on the committee for the prestigious Tezuka Award. In 2019, Dr. Stone won the 64th Shogakukan Manga Award in the shonen category. The series' conclusion in 2022 drew public tributes from numerous fellow manga creators, including the authors of My Hero Academia, Jujutsu Kaisen, and Black Clover, reflecting his standing among his peers.