Mary Sera is the mother of Masumi Sera. She was shrunk supposedly by Apotoxin 4869 (The same poison that turned Shinichi Kudo into Conan Edogawa.) She was once an adult, but now is assumed to be the age of a middle schooler. Not much is known about her, since she tends not to be seen by the public eye. She seems to have a secret agenda along with Masumi Sera that is unkown. She is very smart and knows advanced martial arts.