Ruru Sanjo

Ruru Sanjo more often referred to as Baachan Granny by her tenants is the toughasnails pistolpacking landlady of the Gochiso apartments which double as a school supply store that she also owns. Impressed by Hibikis strong determination she offers to help him in his mission helping him disguise himself as a woman and maintain the disguise throughout his time on campus. In the final episode it is heavily implied that Ruru is a crossdresser as well. Source: Wikipedia