Naruto Gaiden 7 reveals Karin to be Sarada’s real mother, this is done by the help of Suigetsu who tested Karin’s DNA and Sarada’s DNA to see that they have a match. Sasuke suspects that Shin Uchiha is an experiment by Orochimaru, they head towards his hideout to find him to have a new body and explains who Shin is in terms of his past experiments.