Koharu is about Sora's age. She has long and wavy blonde hair with short bangs that expose much of her forehead. Among the company Sora keeps, Koharu has the most buxom figure.
While under the ownership of Kajiwara Shinji, Koharu demonstrated a timid and hesitant personality. After her rescue, she became more optimistic and hopeful. Oftentimes, she would demonstrate a maternal demeanor which could indicate a nurturing and firm handling of her emotions; however, the occasions of her flighty imagination have caused her to be overwhelmed and impulsive. Thus, her emotional frailty is her best and worst feature in that both exude her earnest belief in Sora.
It can be assumed that Koharu had been a possession of the Student Council for a long time because of Shinji's uncommon longing for Koharu, which can be romantic or due to the potency of her weapon. Much of her time before encountering Sora is unknown.
Koharu had first met Sora in shared classes. In an attempted rape behind the Library Self-Study Area, Sora saved Koharu which makes her the first saved "princess". Koharu's role in Sora's life in Utopia Academy exemplified Sora's dream: to be the knight to save the princess. Also, Koharu's weapon revealed the archaic symbol the Student Council President targets. Thus, Koharu had been the first vital piece of the story.
Throughout their plight to rescue all the princesses, Koharu had developed romantic and lustful feelings for Sora. Her overactive imagination often involved Sora "coming on to" Koharu, who remains in denial like most of the girls Sora had saved.
It holds one of the six stars, which are targeted by the Student Council President. Her weapon's star first appeared when Sora fought Shinji for the second time.
This causes Shinji to believe and report that her weapon is bugged to the Student Council. The Student Council views for her weapon nonetheless due to either its strength or the awareness of the symbol's meaning.