How does the author use foreshadowing in Please Look After Mom?

In Part III, Section II, it is important to make note of the reference to the nickel basin and its representation of the emotional bond between Kyun and Mom. This reference foreshadows events in Part IV, in which, the basin plays a catalytic role in events that explore another kind of emotional bond between Mom and someone other than her husband and children or in other words, another secret aspect of Mom's life.