Filmmaker Karan Johar is all praise for the National-Award winning Tamil film "Kaaka Muttai". Johar, 43, was "genuinely moved" by the film, written and directed by M Manikandan. "'Kaaka Muttai' is a gem of a film! Genuinely moved by it... Small film... with a huge heart! Congrats foxstarhindi dhanushkraja," Johar tweeted.