Aki Tsukino

"I never thought I'd be backed into a corner because of a monster like you."

- Aki to Haruka, Episode 11

Aki Tsukino (in Japanese:) is one of the antagonists of the 201 anime Kotoura-san.

Appearance
Aki is a very tall woman with short hair, and almost always keeps her eyes shut. She works as a detective among the Japanese police force.

Her other personality is quite evil and sadistic, which had opened up after many years of pain and jealousy all bottled up from her childhood.

History
Aki was bullied during her schooldays due to her timid personality combined with her unusually tall height. And during all of these years, her split personality developed.

Her split personality became infamous among the town as a serial killer. In Episode 8, Haruka inadvertently reads her mind and faints from the overwhelming images.

Aki finally personally confronts Haruka in Episode 11 and tries to kill her, but is stopped by Manabe. The two manage to hold out just long enough until the police arrive and arrest Tsukino.

Quotes
"When you were talking to this woman earlier, didn't you wonder why she's laughing this whole time?"

- Aki to Haruka, Episode 11

Trivia

 * Aki is what Haruka most likely would have turned into had the latter never met Manabe.