Bleach: Fade to Black

At the outset of this anime - freely adapted from the popular manga of the same name - a violent particle explosion occurs at the Seireitei in Soul Society, destroying much of it at exactly the same moment that a massive transformation overtakes Kuchiki Rukia and causes her to leave something vital behind. Deeply concerned, Urahara Kisuke sends Kurosaki Ichigo into the heart of the society to investigate the disruption; once there he is promptly jumped by a group of ex-ally shinigamis, who now harbor absolutely no memory of Ichigo or Rukia. Ichigo thus finds himself on the run and desperate to find Rukia and identify the source of the said explosion.