It looks like Karai will have a larger role in Teenage Mutant Ninja Turtles 2, as Deadline report that the character has been recast, with Brittany Ishibashi replacing Minae Noji. Karai's origins are never alluded to in the first movie, but there have been several variations of them over the years. In classic TMNT lore she's depicted as being either the daughter or granddaughter of Shredder, but in the new animated series for example, she's is actually Splinter's daughter, who's stolen and raised by Shredder to believe that the Turtles' sensei is the one responsible for the death of her mother.
Ishibashi most recently appeared in TV shows such as Grace And Frankie, Bones and Emily Owens, M.D., as well as features Everything Before Us and The Harvesting.
The actress joins Gary Anthony Williams, Megan Fox, Will Arnett, Stephen Amell, Tyler Perry, Laura Linney and Brian Tee in the sequel to last year's box office smash, which is currently shooting in New York. TMNT 2 (working title "Half-Shell") will be directed by David Green and produced by Michael Bay, Brad Fuller, and Andrew Form. The movie hits June 3rd, 2016.