Spiders are a recurring symbol in Obasan. They represent memory, an important theme in the story. It's notable that when Aunt Aya—the Obasan of the title—goes up to the attic to find a box of journals and letters, that she disturbs a spider's web. As she rouses a couple of spiders from their slumber, Aya is also dredging up painful memories of her experiences during the War. As for Naomi, her own painful memories suddenly appear in her mind almost out of nowhere, just as the spiders themselves scuttle out when their web is disturbed. It's only when she looks up at the ceiling that Naomi realizes the full scale of the spiders' infestation of the attic. And as the traumatic memories of her childhood come flooding back, Naomi also comes to realize just how thoroughly those memories have infested her mind all these years without her being aware.