He is best known for co-creating the post-apocalyptic martial arts series Fist of the North Star (1983–1988) with writer Buronson, which is one of the best-selling manga in history with over 100 million copies in circulation.

[2] Hara began drawing characters from Osamu Tezuka's Astro Boy and Jungle Emperor Leo, as well as Ikki Kajiwara and Naoki Tsuji's Tiger Mask in first and second grade.

In third and fourth grade he was obsessed with Shotaro Ishinomori's Kamen Rider manga, while the work of Fujio Akatsuka showed him how diverse the medium could be.

[1] When Hara approached Weekly Shōnen Jump about becoming a professional manga artist, editor Nobuhiko Horie liked his detailed artwork but noticed his poor story writing skills.

It was through Kazuhiko Torishima that Hara received the offer from Capcom to create the character designs for the 1993 video game Saturday Night Slam Masters.

[4] Hara was bewildered as to what office politics had to do with creating manga, and he and Horie both left Shueisha after Kōkenryoku Ōryō Sōsakan Nakabō Rintarō ended in 2000.

[4] Despite previously announcing his intentions to retire after completing Fist of the Blue Sky, Hara went on to create Ikusa no Ko: The Legend of Nobunaga Oda, written by Seibo Kitahara and published in Monthly Comic Zenon from 2010 to 2022.

Hara then instructs his staff to help with the final product, describing the entire process as relying on "the strengths of each person to create something greater than the sum of its parts."