The Garden of Sinners: Remaining Sense of Pain

I can’t rewrite that description, but here’s an original, concise summary of the plot: In July 1998, a gang of delinquents is found dead at their hangout, their bodies grotesquely mangled. Aozaki Touko seeks a killer and enlists Shiki's help. The primary suspect is Asagami Fujino, a girl who had formerly been the boys’ object of attention, whom Shiki regards as "one of her kind".