About 5 km from Kharapatthar, through a forest road takes you to GiriGanga. If you are driving a car, be cautious. The jungle road is wide enough to cross only one car. You can come back to Kharapatthar before night. Or you can carry tents and rent good blankets from Kharapatthar. Enjoy the views of GiriGanga.
Link of part 1
https://www.tripoto.com/trip/hidden-gems-of-himachal-kharapatthar-6068d3a86e6fe
Link of part 3
https://www.tripoto.com/trip/hidden-gems-of-himachal-kharapatthar-part-3-606ade1d58580