Oka is the president of the school's occult club. She is completely convinced that ghosts, demons, and black magic really exist, and wants to dedicate her life to proving that these things are real.

Oka is absent from school during the first three weeks of gameplay for mysterious reasons. As soon as she returns to school, she is immediately smitten by Senpai. Due to the fact that she falls for him in an extremely short span of time, she believes that there must be something supernatural about him, and begins studying him intently.

She is an awkward girl who is regarded as "creepy" by the majority of the school, but she is actually quite harmless, and some people even find her to be endearing. Perhaps Senpai will think that there is something charming about her unusual nature...