Shunji Sonoyama was a Japanese manga artist and original creator born on April 23, 1935 in Shimane Prefecture. He died on January 20, 1993 from cancer. While a junior at Waseda University, he founded the Waseda University Cartoon Society. After graduating in 1958, he began his professional career as a cartoonist with the humor strip Ganbare Gonbe, also known as Cheer Up, Gonbe, which was later adapted into an anime series in 1980. In 1963, he published Kokkyo no Futari, a collection of gag cartoons, at his own expense.

Sonoyama is best known for creating several manga series that were adapted into anime television productions. His most famous adult strip, Gyatoruzu, also known as Giatrus or Gatapishi, first appeared in 1965. This was followed by Hajime Ningen Gon in 1966. The anime Hajime Ningen Gyatoruz, which serves as a sequel or related series, and Hajime Ningen Gon both derive from these original works. In 1969, he created Hana no Kakaricho, which was adapted as the anime Manga Hana no Kakarichō. Another of his series, Peesuke, was published in 1979. Among his other manga are Sasurai no Gambler from 1969 and Samuraiman from 1980.

A recurring theme in Sonoyama's artistic identity was his view that primitive people were more human than modern individuals. His strips sought to rediscover the human elements lost in mechanized society. This perspective is most evident in his prehistoric gag comics, where characters like Giatrus embody a lazy, crude prototype of early humanity focused on food and basic desires. His work has been described as a comedic, adult-oriented take on prehistoric life. Sonoyama was associated with the Tokiwa-so manga artist residence, having been introduced to that circle by fellow artist Hiroo Terada. Through his long career spanning from the late 1950s until his death, he established himself as a significant creator of humorous manga that successfully transitioned to television animation.