Renko Hikawa

Renko Hikawa (氷河 煉子, Hikawa Renko) is the main female protagonist of the series and a student of Year 1 Class B.

Appearance
Renko is a young sixteen year old girl who wears a large black gas mask and headphones. She has long silver hair and usually wears a turquoise and hot pink parka with black horns on top coupled by a black tank top underneath. Renko also wears a short skirt and black and pink striped socks, and white uwabaki on her feet. When Renko takes off her jacket you can see tribal tattoos lacing up her arms. When she takes off her gas mask, she has blue eyes with red pupils, and has a small canine tooth inherited from her mother Reiko. Renko is also fond of her large breasts.

Personality
She is fairly playful and easygoing compared to the others. She has an obsession with her breasts, and teases Eiri about being flat-chested. She has a more than obvious crush on Kyousuke which goes full blown yandere at certain times. You can hear her cracking jokes occasionally as well as a few childish complaints. Being quite sociable, you can always find her with another student. She originally introduced Kyousuke and the others to Chihiro Andou, Bob, and Kuuga Makyouin.

When she takes her gas mask off, she becomes a full-blown psychopathic killer. All her emotions are linked to killing in this state. The gas mask is just a limiter for her personality. She radiates killing intent in this state too. She is incapable of killing Kyousuke, as he does not love her, despite her love for him. Her wish is to link the emotion of “love” with killing. As Kyousuke doesn't reciprocate her love, she states that she can't hear the killing rhythm.

History and Crime
Renko is an artificial human created by Reiko Hikawa in her line of killing machines known as GMK48. Specifically, the reason for the creation of the line of Murderer's Murderers is to create a team of assassins that can assassinate other assassins.

As Reiko could not bear to see Renko act so inhumanely, she enrolled her daughter to Purgatorium Remedial Academy in order to talk more with humans and learn more about humanity. She still goes outside of school every once in a while to go on one of her jobs.

As her sole reason for existing is killing others, her estimated number of victims is at least in the three digits.

Trivia

 * Renko's last name, Hikawa, can be translated as "frozen river". This might also be a reference to her eyes, which are often described as "frozen blue".
 * Renko's first name can be translated as "molded daughter", in an obvious reference to her being an artificial human.