Importance of Katagiri’s Siblings

Katagiri’s siblings symbolize altruism. Frog notes that, after Katagiri’s parents died, Katagiri put his siblings through college and helped to arrange marriages for them. Katagiri’s siblings never showed any gratitude to Katagiri for all that he did for them, but Katagiri does not seem to mind, as he helped them simply for the sake of duty.