Very little is known about Koyu's personality; however, like the other girls in the Public Morals Committee, she seems to highly respect their leader, Myouri Unzen. She is seen wearing a cheerful expression during her board game with members of the Candidate Student Council.
Koyu has brown eyes and messy, shoulder-length green hair. She wears the standard uniform of an Enforcer.
Thirteen Party Arc
In the lunch room, Koyu and other Enforcer girls question Unzen about the Flask Plan. Unzen identifies Koyu and the others as Specials, then goes on to explain Abnormals and the dice test. Koyu listens along with the other Enforcers as Unzen describes his sister.
Kurokami Medaka's Successor Arc
Unknown Shiranui Arc
Bouquet Toss To The Future Arc
Koyu and several members of the Public Morals Committee confront Medaka as part of the 100 Flowers Run in the Public Morals Committee's office. Her message to Medaka is that her uniform was cute.
Koyu is seen wielding a portable mechanical fan when confronting Medaka.