Police detained 55-year-old Tilak Bahadur Bhandari and four others, aged between 13 and 16, on Wednesday on charges of raping the minor girl over a period of six months.
The accused have confessed to the crime.
The perpetrators raped the girl repeatedly when her parents, landless and impoverished, would go out for menial job, leaving their daughter alone at home, the victim's mother said in her complaint.
The girl was raped for the last time on December 5.