That's a pretty straightforward title and description...Which somehow don't seem related.
Well, you plan on just taking advantage of the guy and getting his money easily, and he ends up turning the tables (in a sense). A rather interesting release, I would say.
Just like them martial arts movies of old, the white-haired old man who looks harmless is oft-times revealed to be the deadliest master. Similarly, ignore this old man's "mojo" at your own peril, Megumi-chan (figuratively speaking, of course).