What is the relationship between Nyasha and the narrator of the story Going to school by Tsitsi Dangarembga?

Nyasha is Tambu's cousin, the daughter of Maiguru and Babamukuru. She has a British education, and finds it jarring to return to Shona society in Zimbabwe. She becomes a guide and a close friend to Tambu when she arrives at the mission. Nyasha refuses to conform to her father's image of womanhood and eventually suffers from a severe eating disorder.