Yamaguchi Yasuo is an animation producer and planner who's become one of the most influential figures in Japanese anime history. He started at Toei Douga's Tokyo Studio in 1963 as an assistant director, eventually moving into the Production Department where he helped develop planning for major series like Wolf Boy Ken, Ge Ge Ge no Kitaroo, Getter Robo, and King Kong.

He's best known for producing Candy Candy, though he actually took on the project reluctantly. When a colleague originally assigned to the series got hospitalized, Yamaguchi ended up stepping in as producer—something he initially resisted since, as he's said, "Like other men, I didn't like shoujo manga, but there were no other relief producers, so I had to take over the project." The series turned out to be a career-defining move. The 115-episode adaptation of Mizuki Kyoko and Yumiko Igarashi's manga became a global phenomenon and essentially established his reputation for producing successful shoujo anime.

After Candy Candy, Yamaguchi produced several other notable works, including Story of Maple Town, Hana no Ko Lun Lun, and Tatsu no ko Taro. When he became chief of production at Toei Animation, he produced the hugely influential Sailor Moon.

In the early 1990s, he co-founded and briefly served as second representative director of the Toei Animation Research Center. He later conducted digital animation research for the Japanese government starting in 1996 and has taught as an adjunct professor at Tokai University. He's also authored several books on anime and animation development.

Today, Yamaguchi serves as executive director of The Association of Japanese Animations, which represents 48 animation production houses and agencies. His deep experience across nearly every aspect of the industry makes him a respected voice for promoting anime globally.