Kenji Yoshida was born on January 1, 1935, in Kyoto, Japan. He is an anime producer, manga artist, and illustrator best known as a co-founder of the renowned animation studio Tatsunoko Production. Yoshida is the younger brother of Tatsuo Yoshida and the older brother of Ippei Kuri (born Toyoharu Yoshida). Together, the three siblings are often referred to as the Yoshida brothers and were central figures in the establishment and operation of Tatsunoko. Before the studio was founded, Yoshida assisted his brothers with their manga work, often using the pen name Kenji Maruyama. He moved to Tokyo from Kyoto in 1958 alongside his younger brother and later helped establish Tatsunoko Production in 1962.

As a producer, Yoshida was responsible for overseeing many of Tatsunoko's major television series. His producer credits include Hakushon Daimaō (known in English as The Genie Family), the historical documentary series Anime-ntertainment Decision, and the original Shinzo Ningen Casshan (Casshan). He also wrote scripts for some productions under his Maruyama pen name. Following the death of his brother Tatsuo in 1977, Kenji Yoshida succeeded him as the second president of Tatsunoko Production, a position he held until 1987. After his tenure as president, he left the company for a period and founded his own entertainment firm before returning in 1995 to serve as the studio's first chairman. He and his brother Ippei Kuri resigned from their positions at Tatsunoko in 2005.

In the context of original creation, Kenji Yoshida is officially credited as one of the creators of the 1975 anime Tekkaman the Space Knight, alongside his brothers Tatsuo Yoshida and Ippei Kuri. This science fiction superhero series, produced by Tatsunoko Production, follows a test pilot who transforms into the titular warrior to defend Earth from alien invaders. While Kenji Yoshida is less known as a solo manga author compared to his brothers, his significance in the industry lies in his role as a producer and executive. His business acumen and production oversight were instrumental in shaping Tatsunoko Production into a major force in Japanese animation, helping to bring numerous influential works to the screen. Through his leadership and production work, he contributed to the foundation of a studio that would go on to produce globally recognized franchises and serve as an incubator for many future industry talents.