The cave swallows appear in a Pet Shop of Horrors side story caled "Dignity", in volume 2 of the Tokyo arc. Count D barely appears at all: it's all about his father mack-daddying it up in college in 1975. There are some rather excellent pants.

As for the swallows...you can tell this one is in charge because she has the fanciest headgear. Apparently when a small human population is isolated in total darkness for thousands of years, they evolve a profound desire to make really ostentatious hats. Based on average number of beads per hank, there are 12,526 8/0 Czech glass seed beads on that thing plus about a pound of glass pearls. I didn't count those. :D