Karan Johar Celebrates Mom Hiroo Johar's Birthday. Hiroo Johar continued the celebrations with son Karan Johar and other friends like Rima Jain, Jaya Bachchan and son Karan at a restaurant in Mumbai reportedly. The septuagenarian cut the birthday cake and posed for pictures with KJo. Hiroo also delivered a short speech to thank everyone in joining in for the celebrations.