Ougi appears to be a girl with short black hair, black pupils, and pale white skin. She is a junior of Koyomi Araragi at Naoetsu Private High School. Ougi often talks to Koyomi about oddities, and helping him remember what he knows. Her catchphrase is, "I don't know anything, Araragi-senpai. It's you who knows."
Ougi is mysterious and can come off as spooky/creepy. She also speaks in a condescending tone towards Koyomi and Hanekawa. Furthermore, Ougi is capable of pulling off many things, despite what she says about what she knows.
Koyomi has a conversation with Ougi in a classroom. After that, Ougi excuses herself, saying that she has a lot of work to do. When Koyomi asks about her job, she tells him that she punishes liars.
Ougi's gender is undetermined as of Hanamonogatari. Suruga refers to them as 'Ougi-kun', 'he', 'this guy', and 'the boy'. She also told Suruga that they have always been a boy since they were born when Suruga asks about it.