Mary is Crystal's mom and the protagonists Mother in-law. She is also Rick's wife and the grandmother of Jasper and Amber.
Mary appears as the shopkeeper in The Denpa Men 3 Rise of Digitoll. Around after you beat Malignus, she announces that her leg is feeling better and she can now join your party. She hires the dwarf that was next to her to run the shop. Most likely, Mary is the one who wrote the message saying that her daughter was kidnapped since Rick didn't know until the protagonist tells him.
Mary has a Catch Antenna, which is also a rare antenna that can catch monsters, however bigger monsters will outsmart, which will make you have to pack catch rate up gear to catch bosses and other big monsters. Mary appears as a yellow Denpa Men which means she is a electric resistance and a earth weaker. She starts off at around your level, not level 1 or else nobody would use her in the coliseum.
Mary has blond hair with pink glasses she also always has a happy face on her look unlike SOME family denpa men.