At the end of 'Asur', the serial killer ie Shubh Joshi gets punished and goes to jail. he was a kid then
But now he's grown up, and returns for revenge
While going to jail as a child, he had decided that when he grows up, he will become a daitya, rakshasa, danava and asura.
Now the aim of Kali Shubh Joshi is to spread Kalyug
He kills one of his fellow escapees from prison by saying that when a man's duty and purpose are over, his body and purpose are of no importance.