This is an interpretation I can get behind. There's some fascinating intricacies here too, such as the usage of "Dango" as the main horror. Far as I can tell, the main connection is in the heads—the round string of them is similar to that of the dessert by the same name.
I'd also go one step further and say that this story is also partially about Yume and Hama themselves. They get closer to "graduating" from grey jobs as they solve their respective parental mysteries, and what happens next? Will they forget each other and join society? From the very premise this story is about the exploitation of workers, bosses preying on their financial insecurity to do inhumane things, treating them as victims or as disposable. What does it mean for Yume and Hama to escape that life? I imagine the author struggles over such things as well.