Kokona Haruka is a cheerful and friendly young woman who participates in the Drama Club at Akademi.

She is known around school for her eagerness to help others in need. If the Cooking Club needs someone to taste-test a new dish, she is the first to raise her hand. If the Science Club needs a test subject for their latest dangerous experiment, she volunteers without hesitation. This has led a few students to give her unflattering nicknames such as "test dummy" and "guinea pig," but she doesn't really see this as anything to be ashamed of.

There was once a point in time when she had a crush on Taro Yamada, but it was short-lived; she realized that the two of them had nothing in common, and moved on. It is very fortunate that she did not decide to pursue him; if she had remained interested in him, her life would have been in grave danger the following year, when Ayano developed an infatuation with Taro.

Kokona joined the Drama Club because of her deep admiration for the club's leader, Kizana Sunobu. (This admiration runs so deep that Kokona is willing to tolerate or outright ignore Kizana's numerous personality flaws.) Kokona's "twin drill" hairstyle was inspired by Kizana, who often styles her hair into very large ringlets.

Kizana chooses to style her hair differently every day of the week, rather than commit to one hairstyle. She does not feel offended that Kokona has chosen to use one of her hairstyles - however, Kizana values originality and creativity, so she feels that Kokona should develop her own original style rather than imitate what she sees others doing.

Kokona enjoys stageplays immensely, and has begun writing a play of her own - a story about a serial killer. Despite the fact that Kokona is a very bubbly and lighthearted person, her serial killer play is actually quite dark and morbid, which surprised her fellow clubmembers a lot. Kizana considers Kokona's play to be distasteful, and has strongly discouraged her from pursuing it.

Because of her cheery attitude, nobody would ever guess that there are numerous problems in Kokona's life; her father is in debt to a loan shark, and the amount of money he owes is astronomical. In an attempt to help her father, Kokona has recently begun to participate in "enjo kōsai" - the practice of dating older men in exchange for money and gifts. She gives the money she earns to her father.

Kokona is completely unaware that one of the other students at school is actually the daughter of the loan shark that is extorting her father. Despite her friendly nature, Kokona feels such intense anger towards that loan shark that - if manipulated or provoked in the right way - it's entirely possible that she could be convinced to harm or even kill the daughter of that loan shark...