Between 2010 and 2015, Inagaki collaborated with several artists, including Bonjae, Katsunori Matsui, and Ryoichi Ikegami, and published one-shots in different magazines.

[5] He started his career as professional manga writer by publishing works in Shogakukan's Big Comic Spirits.

[8][9] He later moved to Shueisha's Weekly Shōnen Jump, in which he won the 7th "Story King" award for a storyboard of Eyeshield 21.

[1][10] When he planned to create Eyeshield 21, the editorial department asked if he wanted to both write and draw the series, but Inagaki felt he was "so rookie".

[19] It has sold more than 20 million copies in Japan,[20] has been published in seven countries, including in the United States,[a] and gained an anime adaptation that aired for 145 episodes from April 2005 to March 2008 on TV Tokyo.

[30][31] For the release of Eyeshield 21 anime he created the Kome Studio, a company of copyright management to ensure the right of the original creators of manga.

[4][36] Along with Ryoichi Ikegami, he published the one-shot Kobushi Zamurai in Shogakukan's Big Comic Superior on August 12, 2015.