A native of Tokyo, Hara attended Hongo Senior High School and worked as an assistant to manga artist Yoshihiro Takahashi after graduating. As an amateur, he won the first prize of the 33rd Fresh Jump award for his one-shot Super Challenger. Hara's professional career began with his first published work: Mad Fighter in 1982. His first serialized work in the Weekly Shōnen Jump was the Iron Don Quixote, which lasted only ten weeks in serialization. He achieved fame after the publication of Hokuto no Ken (Fist of the North Star) in 1983, which he co-created with Buronson and ran for six years in Weekly Shōnen Jump. After its completion, he worked on shorter series and one-shots, including three different adaptations of Ryu Keiichiro's novels (Keiji, Tokugawa Ieyasu and Sakon). One of his recent works is Sōten no Ken (Fist of the Blue Sky), a prequel to Hokuto no Ken, which was serialized in Weekly Comic Bunch from 2001 until the magazine's final issue in 2010. He suffers from keratoconus.
Saturday Night Slam Masters/Muscle Bomber (1993 arcade game) - promotional illustrations. The character portraits in the arcade version were done by another artist, but they were replaced by Hara's own renditions in the console versions for the Super NES and Sega Genesis.
Muscle Bomber Duo (1993 arcade game) - promotional illustrations
Ring of Destruction: Slam Masters II/Super Muscle Bomber (1994 arcade game) - promotional and in-game illustrations.
Itadaki Muscle! (2006 TV series) - illustrations for the opening intro.
Mori no Senshi Bonolon (2006 anime series) - producer, character designer
Gifuu doudou Naoe Kanetsugu (2008 manga series) - Co-author with Horie Nobuhiko, illustrations.