The accused have been identified as Amit Sonkar, Kuldeep Sonkar, Bhim Sonkar, Manjeet Sonkar and Ankur Sonkar, Senior Superintendent of Police Yashsavi Yadav said.
Three pistols and six cartridges have been seized from their possession, Yadav said, adding that they were arrested from near a cotton mill.
Rajiv, alias Raju Mishra, was shot dead by five motorcycle-borne assailants on January 3 this year in the Juhi area.
Mishra was talking with some people on the road when the assailants opened fire. He took four bullets and died on the spot.