Booked for criminal conspiracy, Kumar was produced in Narwana court and sent to two-day police custody.
His wife Meenu (30), the victim's aunt, was arrested on Saturday after the victim set herself afire.
The police had already arrested three accused - Pardeep, Navin and Sanjeev.
Meanwhile, AS Chawla, inspector general of police, Hisar range, and Jind superintendent of police Saurabh Singh reached the village on Monday and met the victim's family and other villagers for further investigations.
Chawla assured the victim's family of complete protection and strict action against all accused and deployed two state policemen outside their house.
Later during the day, workers of the Haryana Janhit Congress, led by its state president of women wing Kusum Sharma, took out a protest march against chief minister Bhupinder Singh Hooda and burnt him in effigy at Narwana Aggarsain chowk.
Workers of the Bharatiya Janata Party and Haryana Janhit Congress demanded strict action against rapists and slammed the government for failing to put a check on crime against women.