Nanako and Nanao the Day They Became Sister and Brother

Nanako is an ordinary high school girl who lives with her mother who is a taxi driver One day suddenly she has a younger brother Nanao the son of her late fathers mistress While Nanaos mother is being put in jail Nanakos mother decides to take care of him Nanako doesnt like it at all Everything Nanao does irritates her Shortly afterwards Nanakos mother becomes very sick In fact she doesnt have much time left Since she is in hospital Nanako is forced to live with Nanao alone