|Debut|| Episode 1|
Murder at the Ball
|Japanese voice||Takako Honda|
Izumi is a tall and slender woman. She has dark blue eyes and black hair. Her hair is parted on the right. The right side of her hair reaches her shoulder, while the left side is shorter and only reaches her mouth.
She wears a dark green suit. She has a green vest, buttoned over a white shirt. Her shoes are black.
A public prosecutor with a no-nonsense personality, Koyama often calls on Rinroku for help in solving cases. She does not think fondly of Shinjuurou, and even less of Inga.
Not much of her past is known.
Hayami Seigen falls in love with her.