Director Karan Johar, who is ready to launch four new actors in his upcoming directorial "Student of the Year", says it is a huge responsibility on him. The film is the 40-year-old's first directorial venture without actor-friend Shah Rukh Khan in the lead and will mark the debut of Mahesh Bhatt's daughter Alia Bhatt, director David Dhawan's son Varun, Siddharth Malhotra and actor Boman Irani's son Kayoze. "The film is a big responsibility for Dharma productions.