User blog comment:Xilinoc/Ch. 591 - Marching Out the ZOMBIES 2/@comment-24572618-20140730210458/@comment-3219912-20140804080157

Well Bambi and Toshiro (mostly likely at least) were both zombified the previous day. So perhaps the dark skin is just a result of being zombified longer than the Shinigami she just recently has been stockpiling.