Koharu has short reddish hair and bangs. She is said to be cute, but she herself admits that she is not as cute as Suiren.
Koharu is very energetic and straightforward, but can be a bit childish and arrogant, such as when she confessed to Kawasumi, she first arrogantly asked, "Do you want to date me or not?" but when he rejected and attempted to run away, she became desperate and started yelling out. "Please date me!"
Despite her carefree attitude, she can be very determined and serious, mostly when it comes to Kawasumi, or anything else she greatly cares about.