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.

Spoiler

As of Hanamonogatari and afterwards, chronologically, Ougi refers to himself as a boy. Others will question Ougi's identity when they first meet him as they knew him as a girl before, but they all shrug it off and seem to doubt themselves as to whether he was a girl before. An example being when Suruga asks about it and was told that he has always been a boy since he was born. Nadeko and Koyomi have also have a similar experience. Suruga herself refers to him as 'Ougi-kun', 'he', 'this guy', and 'the boy'. As of Musubi, Ougi seems to be a girl once again, now remaining in the classroom seen in Ougi Formula.

Spoiler

The reasons for this seems to be due to Ougi connecting to Suruga after Koyomi graduates, therefore becoming her other side. Thus, Ougi becomes a boy and seems to pretend its the first time he meets everyone afterwards. After Suruga herself graduates, it's likely that Ougi no longer has anyone to connect to and becomes a girl that guides others in the odd classroom.