Gustav

Gustav (グスタフ) is the pet of an unnamed Tokiwadai Middle School student.

Toaru Kagaku no Railgun Gaiden: Astral Buddy
Junko sees that Misaki is missing her bag, to which Misaki responds that it has been stolen. In a flashback to her wandering about the Indian Poker cards, her bag is suddenly stolen by a lemur, and though she tries to run after it she become easily tired and delegates the task to other girls instead. Misaki in the present time tells Kobayashi Satori to take command and not allow the lemur to escape Tokiwadai. The girls of the clique find the lemur. As the clique wonders about what they should do with the lemur. Misaki thoughts dwell on how someone would use their power to control the lemur and steal her bag.

Later, the girl who ordered the lemur to steal Misaki's purse is talking to a tree, asking for advice after her lemur got captured. Suddenly, her lemur comes scurrying right back to her. Just as she grabs it, she comes under the power of Shokuhou Misaki, the Mental Out.