In the near future, for the sake of social stability, a technology called "forgetting surgery" has emerged to strip people's painful memories and seal them in a lighthouse on an isolated island at sea. Ayu is the only keeper of this lighthouse, receiving and archiving those memory crystals full of sadness day after day. He has no past, only rules. Until one day, a crystal emitting a familiar temperature arrived. When he violated the prohibition and touched the secret hidden inside, he found that he was guarding not only the past of others, but also the only key to the truth of his own identity. A confrontation with a huge organization and his own forgetfulness begins.
