Kiminori Wakasugi was born in Oita Prefecture in 1975. He decided to pursue a career as a manga artist during his final year of university. His professional journey began in 1998 when he received an Incentive Award from Young Magazine, a monthly manga award. In that same year, he made his debut with a work titled Boku no Migite wo Shirimasenka? (Do You Know Where My Right Hand Is?) in the magazine Young Magazine Zokan Aka BUTA. Following his debut, Wakasugi spent five years working as an assistant to the established manga artist Yasuhito Yamamoto. His first serialized work, Amaresu Ken-chan (Ken the Amateur Wrestler), was released somewhat irregularly in 2004 in the pages of Young Magazine Uppers, though it did not achieve significant success.

Wakasugi is best known as the creator of Detroit Metal City, a black comedy and parody manga series that he wrote and illustrated. The series was first published as a one-shot in Hakusensha's seinen manga magazine Young Animal in April 2005. Due to its positive reception, it began regular serialization in the same magazine from September 2005 and concluded in April 2010. The complete series was compiled into ten tankobon volumes. The story follows Soichi Negishi, a shy and gentle musician who dreams of a career playing Swedish-style pop music but is forced to perform as Johannes Krauser II, the demonic frontman of a popular death metal band, leading to a conflict between his true aspirations and his stage persona.

The success of the manga led to multiple adaptations. In 2008, a twelve-episode original video animation (OVA) produced by the acclaimed animation studio Studio 4°C and directed by Hiroshi Nagahama was released. Later that same year, a live-action film adaptation directed by Toshio Lee premiered in Japanese theaters. Wakasugi was involved as a screenwriter for the 2008 live-action film. The manga was licensed for English publication in North America by Viz Media, and the OVA was licensed by Sentai Filmworks.

Beyond Detroit Metal City, Wakasugi has continued to create manga and work in film. He was the creator and original author of the manga series Minna! Esper Dayo! (also known as The Virgin Psychics), which began serialization in 2009. This series was later adapted into a Japanese television drama in 2013, for which Wakasugi served as the original author and a screenwriter, as well as a film adaptation in 2015. Another of his notable manga series is Kappei, which he serialized from 2011 to 2014. This action-comedy series was adapted into a live-action film titled Kappei, also known as末日战士, which was released in 2022 and for which Wakasugi was credited as a screenwriter. He is also the author of the manga series Ashita no Esa Kimi Dakara, which began publication in 2019.

Wakasugi's artistic identity is often linked to a distinct visual style and a penchant for parody, as seen in the explicit dialogue and exaggerated 1980s-era manga parodies present in Detroit Metal City. His work frequently explores the contrast between a character's ordinary life and an extreme, often ridiculous, secret identity, blending crude humor with surprisingly sincere moments. Despite his subject matter, he has been described as a fan of pop music and not particularly knowledgeable about heavy metal, which contributes to the outsider, satirical perspective of his most famous work. His manga Detroit Metal City gained immense cult popularity, particularly on the internet, and was recognized as a top boys' manga in the Kono Manga ga Sugoi! rankings in 2007.