Age: 33 Birthday: September 10, 1985 She is one of Ashirogi Muto's assistants, along with Takahama and Ogawa. She is their only female assistant. She has one year of experience with shounen and one year of experience with shoujo. She gains experience throughout the series as she becomes an assistant for Takahama's Business Boy Kenichi, Aoki Kou's A Time of Green Leaves, and then later back to being assistant for Ashirogi Muto's PCP after one of their assistants gets serialized.
The series' protagonist. A young arms dealer and the daughter of Floyd Hekmatyar, a global shipping magnate . Belongs to HCLI's European and African Logistics Division. She is physically attractive, with long silver-white hair, pale alabaster skin, striking blue eyes and her trademark smile, which is present even under dire circumstances. She is extremely charismatic and bold, which earned her great success in her business as well as the fierce loyalty of her subordinates. While generally behaving in a bubbly and slightly childish manner, Koko is actually rather ruthless and has been called a 'monster' by various characters. R reveals that she has never shown her true emotions since he met her. Before the series, she showed far more emotion, begging her subordinates to save her when Hex attacked her. However, after Echo's death, she took his final words to heart and keeps smiling no matter the situation. Koko has shown deep attachment to her team in general, going so far as to use Jormungand to save them. She considers Jonah a little brother and is very affectionate towards him. Valmet has a crush on Koko, but whether Koko reciprocates the feelings is unknown. She has a soft spot for R and Echo. She hates her father, Floyd Hekmatyar, as he was the one who pushed his children in arms dealing.
She is a Japanese expert in robotics, working for Koko and other companies (though she wanted to use her knowledge to make toys at first). She is also a butterfly fanatic and spend most of her time hunting them. She and Koko have a secret plan going on codenamed "Jormungand". (Source: ami)
Chiyuu is an artist and is friends with Birthday and Ratio. Her Minimum Holders is making her self blend with the environment like a chameleon. She can also make someone else turn invisible when they are near her. To active her Minimum, she has to say a color.
Ruri is Sango Himeyuri's younger twin sister. She loves her sister very much and believes that they only need each other. She dislikes Takaki and treats him like a pervert when he helps Sango. She does not want anyone interfering in her life with Sango. But otherwise, she is a nice girl who only wants her sister's happiness.
Youko entered Lillian during her first year of middle school. Despite coming from an outside schooling system she was asked to give the welcome speech for first year students. She is characterized as being calm but sharp with a mischievous side, in the manga she is described to be "lily" like. Her greatest day was seeing the Rose Mansion filled with ordinary students during the Bouton's card hunt. During Youko's second year of high school, Rosa Gigantea and Rosa Chinensis (Sei and Youko's onee-sama's respectively) tricked Youko into taking an interest in Ogasawara Sachiko. Sachiko, Youko noted, always walked looked like she was fighting internally with something. With an endless desire to help (or meddle, as Sei put it) people Youko took Sachiko as her petite soeur. She had Sachiko quit her after school lessons (or in the novel, hinted about it) and once scolded her for not expressing her emotions and opinions. Much like Sachiko did to Yumi. Prior to graduating, Youko took Yumi aside and asked her to look after her stubborn and "uncute" little sister. Then later during Sachiko and Yumi's separation she felt slightly jealous of the close bond between them. Youko considers herself to be Sachiko's onee-sama even beyond graduating from Lillian. Aside from her petite soeur Youko is probably closest to Satou Sei. They met during middle school when Youko approached Sei about joining clubs. Sei asked if Youko too felt alienated from the class but Youko said she simply became interested in Sei. Disinterested in this, Sei called her a meddler. During Sei's relationship with Shiori it was Youko who constantly tried to reach out to Sei. It was also Youko who asked Shiori to leave Sei a letter when she left. Fans have speculated that Youko has an unrequited love for her friend and the Sei/Youko pairing is very popular within the fandom. After graduating from Lillian, Youko attends law school. She tearfully admitted that she would have liked to attend a liberal arts college but it wouldn't have enabled her to help people.