Karai is a member and leader of the Foot Clan Japanese branch, and, following the events of City at War. She became the leader of the Foot Clan New York branch. She's sometimes the daughter of the Shredder, and is one of the Ninja Turtle enemies. Despite her being an enemy, Karai has helped the Turtles on more than one occasions.
Karai appears as the adopted daughter of The Shredder. After his apparent demise, she temporary took on the persona of The Shredder. She is shown to be a loyal servant towards the Shredder, but is willing to betray him and side with the Turtles, if his goals are going too far. This creates opportunity for her to team up with the Teenage Mutant Ninja Turtles, especially Leonardo, and shows her struggling with allegiances. Karai is a deadly warrior, but inside is a kind heart waiting to be released.
Main Article: Karai (2012 TMNT)
Karai appears as the adopted daughter of the Shredder. However, unlike other adaptations, Karai is the daughter of Splinter, her real name is Miwa, but was kidnapped and raised by Shredder to be used to kill Hamato Yoshi. Shredder also lied to her that Splinter killed her mother, in which she seeked to avenge her mother' death. She eventually discovered her true origins and that Shredder was the one responsible of the death of her mother. She then seeked revenge on Shredder. This resulted in her getting captured by the Foot Clan. When the Turtles tried to rescue her, Karai ended up falling into a vat of Mutagen, resulting in her turning into a mutated snake-like creature, which she can semi-revert back into her original self.
TMNT the Movie
In this adaptation, Karai is the new leader of the Foot Clan, after the Shredder was killed. She, and her army were hired by Maximillion Winters to capture 13 monsters so he could break a curse that Winters and his brethren unleashed thousands of years ago. Some time after the Stone Generals betrayed Winters, Karai and the Foot were offered by Aguila to join them. Karai explained that the Foot works for Winters and not for them. While the Turtles were confronting the Stone Generals, Karai, the Foot, April O'Neil, and Casey Jones went to find the 13th monster to end the curse. After they were successful, Karai disappeared on good terms with the Turtles.
Main Article: Karai (Paramount film)
Karai makes a brief appearance as the tertiary antagonist in the 2014 film; Teenage Mutant Ninja Turtles. She is portrayed by Minae Noji.