Merchandisium trades in commodities produced by other Psymonsters to earn a profit. He likes expensive objects, adores food, and he is crazy about broken things, but what he really loves are things that are extremely gainful. He takes excellent care of his precious things, making sure that any Psymonster has always kept at the correct temperature and fed the right food, and in return any Psymonster helps him to show the audience some of his fabulous merchandise. All he has to do is display his magical abilities by shrinking all of the priceless possessions, so that they can fit into his merchandise backpack. It may look unpredictable, but Merchandisium has had lots of magical powers, and he is very wise. Though he isn't completely fearless, he hasn't yet worked up the nerve to ask the treacherous Psymonster out on a date.
He is a handsome merchant with tan skin, teal eyes, white hair, a mustache, and a beard, a red turban with a green jewel, a blue robe with an orange sash tied around his waist, regal gold patterns on his sash, a green bandanna, a purple merchandise backpack with maroon shoulder straps, and yellow slippers.
- The name "Merchandisium" is probably derived from the word "merchandise", meaning goods to be bought and sold.
- Like Tireslasher and Undergrounder, Merchandisium wears a backpack