Mizu Haninozuka is Mitsukuni's younger sister.
Amaya Morinozuka is Takashi's younger sister.
Together, these two friends and unrelated twins are the best team put together by the Government funded Underground Private Academy, until they were expelled that is.
They keep secrets to themselves as they dodge the hits that are made by others, they fear for eachother's life and welfare.
Their brothers seem to think they need to mix in with the other students, but they try to keep to themselves. Slowly people leak their way into their walls, and danger starts to grow in the shadows.
When they least expect it, they strike. And one of them doesn't make it through their first attack unharmed. And that's when things get interesting.
