Who is Grandmother from Lost Names: Scenes from a Korean Boyhood and what is their importance?

Grandmother is the name that refers to the boy's paternal grandmother. She believes her mission is feeding the family. Consequently, she gets up early on Sundays to fix a big breakfast for everybody. She serves soup, eggs, squash, beef, fish cucumber, eggplant, cabbage, rice and other food. When her daughter-in-law visited her parents to have a baby, grandmother took over fixing lunch for the boy and his sister. Grandmother wants her family to live better that she did which was why she and grandfather worked hard to provide for them. She feels bad that they can afford rice, chicken and meat now, but can't have them since Japan took over. Consequently, grandmother takes pride in putting white rice in his lunch box. She doesn't know that the other boys tease him and take his lunch because it has white rice like rich boys get. He doesn't like white rice in his lunch because it makes him feel like he's showing off. Grandmother gave him a hot sweet potato to keep him warm on a cold day to school and to eat as a snack later.