I wanted to draw everyone dressed up. Here's averyone left to right, top to bottom:

-Boluomeng is Aka Manto: A yokai who kills people who use bathrooms lacking toilet paper with an unwinnable decision between red or blue toilet paper (but replaced with candy bowls because he's a good host)
-Andy is Nicol Bolas: A main antagonist from Magic: the Gathering
-Daichi is Reaper of Tooting: He couldn't think up of anything and threw a blanket on himself while carrying a scythe
-Medrash is a magician: While a little humiliating, he is dressing up as someone who only wishes he could do what Medrash can
-Deneb is someone making a hard moral decision: They have an angel on one shoulder, devil on the other, and hanging over Deneb is a complex math equation, as if they are calculating who to listen to
-Cutlass is a wizard: They didn't really know what to do and went with something simple, but feels childish doing so
-Daisuke as a Mad Max esque biker: I don't know much about Mad Max, but I know Daisuke likes to wear a lot of leather, and I've imagined him doing movie stunts on a motorcycle while styling YuGiOh 5D's style gaudy, leathery clothing.