We're lumping these characters together because they go together like salt and pepper; incidentally, salt-and-pepper is the color of their hair. Zing!
Poor Grandma Nakane. This lady is Naomi's fraternal grandmom, and all we know about her is that she was yasashii, just like Naomi's mom. The internment camps were not made for yasashii people, and she goes crazy while she's there. The way that Aunt Emily finds Grandma Nakane in the internment camp is an eerie foreshadowing of Grandma Kato finding Naomi's mom in the wreckage of the Nagasaki bombing.
This is the reason that the Nakanes are in Canada to begin with. He was the first of Naomi's grandparents to come to Canada in 1893. He was a top-notch boat builder, and has one arm that is unable to move.
He is swept up along with Grandma Nakane when they are visiting friends on Salt Spring Island and sent to the internment camps. He dies of a heart attack the day before the family leaves Slocan.