Born at Nattathi near Srivaikundam in 1924 to a farmer, Chinnasamy, Nainar grew up as a staunch Gandhian. He public life began in the early 1950s. He was involved in the Bhoodan movement launched by Vinoba Bhave.
Then he continued with all the land reform movements and served as District Secretary of Indira Congress in 1970s. He had also contested in the 1977 Assembly elections at Srivaikundam constituency but lost the elections in a small margin. A multifaceted personality, Nainar had also worked as a journalist in one of the Tamil dailies.
He has written several books about problems faced by the ryots and the river water. He regularly visited Thoothukudi Collectorate on Mondays to submit grievances of not just farmers but also of the people of his village.
He had two associations, one for the farmers, Thoothukudi District Tamirabarani River Water Protection Council, and another for the village people. In one of his books, ‘Tamirabarani River and the Rights of the Farmers’, CPI leader, Nallakannu, had written that Nainar Kulasekaran had protested for the rights of the farmers for more than five decades. Naninar had been ailing for the past six months before he died on Sunday. Gunaseelan, an AAP functionary and environmental activist, said that Thoothukudi district had lost an activist, who had fought to save the Tamirabarani River.