Symbolism, Imagery, Allegory
For decades, Henry's been searching for this one Oscar Holden record to no avail. His son knows that he's obsessed with finding the record, but he has no idea why it's so important:
"That's been Pop's Holy Grail—rumor is they printed a handful back in the forties, but none survive today," Marty explained. "Some people don't even believe it ever actually existed, because when Oscar died, he was so old even he didn't remember recording it. Just some of his bandmates, and of course Pops here—" (23.60)
The truth is that Henry doesn't care about the record because of the music on it; he cares about it because of what it represents. The recording is of a song that Oscar Holden played for him and Keiko on the night they snuck into the Black Elks Club, and it reflects the shared memories and love they have for each other. The elusive nature of the record—how people aren't even sure it existed—is kind of like Henry and Keiko's relationship: It happened so long ago and faded into nothing at all (thanks to Henry's dad intercepting their communications), so it's little more than a memory in Henry's head.
When Henry thinks about the record, he remembers how Keiko saved up all her money to buy him a recording as soon as it came out:
Henry was speechless. His jaw hung open, but no sound came out.
"Can you believe it?" She gushed with pride. "This is our song, the one he played for us!" (24.23-24)
The song on the record is "their" song, a memento of their love that Henry desperately wants to excavate again. Of all the things Henry and Keiko share—cafeteria jobs, being on the receiving end of racism—their time listening to jazz remains a highlight for Henry so many years later.