Yudetamago is the collective pen name of the Japanese manga artist duo consisting of writer Takashi Shimada and artist Yoshinori Nakai. The pair are best known as the original creators of the long-running Kinnikuman franchise, which spans multiple manga series, anime adaptations, and a vast merchandising legacy.

Takashi Shimada was born on October 28, 1960, in Osaka's Nishiyodogawa Ward, while Yoshinori Nakai was born on January 11, 1961, in the Nishinari Ward of Osaka. The two first met in 1971 during the fourth grade at Osaka Municipal Suminoe Elementary School and later attended the same middle and high schools, where they began collaborating on manga as a creative team. Their partnership was influenced by the successful duo Fujiko Fujio, inspiring them to pursue a professional career in manga. While still in high school, they submitted works to major contests, including Gong desu yo for the Akatsuka Award and Mammoth for the Tezuka Award. Although neither submission won, the efforts caught the attention of an editor at Shueisha, leading to their professional debut.

The duo's breakthrough came with Kinnikuman, which began serialization in Weekly Shōnen Jump on May 28, 1979. Initially conceived as a parody of Ultraman and other tokusatsu heroes, the series evolved into a wrestling-focused action manga and became a major hit. The series ran until 1987, spanning 387 chapters collected in 36 volumes, and won the Shogakukan Manga Award in 1984. The success of Kinnikuman spawned a multimedia franchise, including a popular anime adaptation by Toei Animation that aired from 1983 to 1986, as well as multiple animated films. The series also generated a massive toy line known as Kinkeshi in Japan, which was later exported to North America as M.U.S.C.L.E..

During the original Kinnikuman serialization, the duo also created the spin-off Tatakae!! Ramenman, which focused on the popular supporting character Ramenman and was serialized from 1982 to 1989. Following the conclusion of the main Kinnikuman series, Yudetamago created several other manga across various genres and publications, though none achieved the same level of commercial success.

In 1998, the duo revived the franchise with Kinnikuman Nisei, also known as Ultimate Muscle: The Kinnikuman Legacy, which was serialized in Weekly Playboy and aimed at the now-grown original fanbase. This sequel series focused on Mantaro Kinniku, the son of the original protagonist, and later received its own anime adaptation that premiered in Japan in 2002 and was subsequently broadcast in North America by 4Kids Entertainment. The anime was notably more successful in the United States than in Japan, leading to additional episodes produced specifically for the American market.

In 2011, Yudetamago resumed the original Kinnikuman series after a 24-year hiatus, with new chapters published online through Shueisha's Shū Play News platform, continuing the story from where it had left off. This revival has led to new anime adaptations, including Kinnikuman: Perfect Origin Arc, bringing the long-running franchise to contemporary audiences.

Throughout their career, the division of labor within Yudetamago has been clearly delineated, with Shimada serving as the story writer and Nakai as the artist, a dynamic established during their school years. Their artistic identity is characterized by a blend of humor, exaggerated character designs, and wrestling-inspired action sequences. The duo's work has had significant industry influence, pioneering the wrestling manga genre and contributing to the broader boom of fighting-themed manga in the 1980s. With over 75 million copies of Kinnikuman-related manga sold and decades of continuous creative output, Yudetamago remains one of the most enduring creative partnerships in the history of Japanese popular culture.