violence, cursing , sadistic , blood , crazy , insane , at the beinging the store yn and accelerator are friend at the childhood , they promise that they alway have other back even they are dead they still friend. one day there are some stranger face kidnap yn and accelerator and they experiment on both yn and accelerator , they both are in pain when the experiment done when accelerator see a science did to yn his was very angry and kill anyone who hurt yn and his take yn out of the building , when they out accelerator kill the stranger again and protect yn from any harm. and on that day accelerator promise that he protect yn from any harm.