A fine example of lampshading if there ever was one.

(Standard disclaimer about TVtropes sucking away the rest if your day if you follow that link.)

Letty = Olaf
Yuuka = Spike
Momiji = Andy? (closest I can find off Wikipedia, anyway)

Also, first time for Chamupei to draw Peanuts-style Momiji, I believe.

Moonspeaker said:
Momiji = Andy? (closest I can find off Wikipedia, anyway)

Yep.

I wonder who Belle and Marbles would be...
If I had to guess, I think Marbles would be either Kokoro (being a relatively new youkai), a resident of the underground, or a PC-98 character.
Belle I'd say would be Eirin, but that's only because of her role in Snoopy's WWI fantasies.

Pretztailfan95 said:

I wonder who Belle and Marbles would be...

According to post #1629174, Hina and Yamame, respectively.