Mishima's paternal grandmother possessed a strong will and a vivid imagination to match. She was a person of extravagant and expensive tastes. Among other things, she instilled in her grandson a love for the Kubuki theater, a passion that Mishima would have throughout his entire life. Many of his Noh plays , of which he was considered by many his fellow writers to be the modern master, were the result of this exposure by his grandmother.
But in spite of all this, she was a very unhappy woman. According to some Mishima biographers she felt humiliated by her husband's lack of pride. Mishima's grandfather was a civil servant who had become involved in a corruption scandal. As a result, he had to resign his post in the government. As time wore on , the family assets dwindled to almost nothing until finally the Hiroaka family had to sell almost everything, including their family home, and move to a rented house in Tokyo where Mishima was later born,
Towards the end of her life Natsu Hiroaka suffered from a variety of ailments and Mishima became her nurse as well as companion. Mishima would often accompany his grandmother on her walks and she would only take her medicine from her "little tiger" as she liked to call her grandson. As time went on the pain from her illnesses would send her into screaming outbursts, mostly at night, where Mishima would have to comfort her until she calmed down.
In January of 1939, a few days after Mishima's fourteenth birthday Natsu Hiroaka died from hemorrhaging ulcers,