Akira and Haruka Okumura are the sisters of Rin and Yukio. The boys had never known of them. Only Mephisto Pheles, Shiro Fujimoto, and Tatsuma Suguro, who raised the girls with his son Ryuji, or Bon.
How do the Kyoto Trio react when Yukio and Rin finally meet the girls they had lived with their entire lives? Will they be surprised that they look so much alike? Or will they quickly figure out that both sets of twins are actually related, making them Quadruplets?
Akira, like Rin, has the power of Satan's blue flame. Although she has it fully controlled, it is still a secret that only she, Haruka and Tatsuma share. Her sword, Aoikage (Blue Shadow), is much like Kurikara, except the fact it can split into two seperate swords. Akira uses her powers to help people, not hurt them. She has trained her body to repel Satan, making him unable to use her body as a host.
Haruka, being the youngest twin, and youngest Quadruplet, often feels left out and tends to train more than necessary. Her body is strong, but her mind is strongest. She is one of the smartest people you could ever meet, and she tends to leave Akira in the dust when it comes to academic skills.
