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

Grandfather is the name that refers to the boy's paternal grandfather. The boy's father brings the family back to Korea to help his father with the farming and family orchard. The grandfather and father share a secret from the boy until he is older that makes the grandfather proud. Grandfather has dinner with his son and grandson on two occasions. On the first occasion, grandfather warned the boy Japanese will be mean to him but not to cry and he got no wine. On the second occasion, he received a cup of wine from grandfather that signified his pride and honor at his grandson becoming a man by defending his son's honor. On a third occasion, grandfather, father and son are on their knees, crying at their ancestors' gravesite, where they pour cups of wine over their graves and drink a cup. Father and son let grandfather pray alone. He joined them and three generations bowed to their ancestors and return home February 11, 1940, the day they lost their name.