Hringni Tongsin joined NSS (National Service Scheme) in 2010. Together with her younger sister, Hmanni Tongsin Anal, she joined the Assam Rifles in 2015. After undergoing tough and rigorous military she became a Riflewoman in April 2016.
Hringni has been actively involved in border guarding duties along the Indo -Myanmar border and also been part of various Counter Terrorist operations launched by Assam Rifles in Manipur through 2017-18. She is presently posted with the Assam Rifles Field Intelligence Unit (ARFIU). Beside being good in sports and outdoors, Hringni has represented the Force in the Inter Central Armed Police Forces (CAPF) Debate Competition on Human Rights conducted in 2019 and secured the first prize in English category (Delhi Zone) held at Delhi.