This little family is not the only one subsisting on the leftovers and prospects of the cremation ground. The houses are all rather leaky with holes and gaps, and the people all kind of spy on one another. We slowly come to understand that there is something unusual in Toradoi's house which is causing quite a stir of gossip and spying on her household. At first she just refers to it as a "black box," but then we learn is it actually a wooden chest. The narrator explains the chest's presence this way:
Its very existence was a source of strength to Toradoi.
As the descriptions continue, we learn that this box is ornately carved and is quite large. Then we get this line, and we understand exactly what the wooden chest is:
she wriggled into the huge chest and lay there, leaving its cavernous mouth open.