The man code-named "Zero" woke up on an isolated island made of gray sand and lost all his memory. The only living creatures on the island are the mysterious girl "tide" and a crystal tree that can reflect memory fragments. This island is not a real existence, but a carefully constructed mental cage. Whenever Zero touches the leaves of the crystal tree, fragments of the past flood into his mind - who is he? Why here? What role does tide play? In order to find himself, Zero must dive into the depths of his own consciousness and piece together the truth that has been deliberately forgotten. However, he soon discovers that some memories are buried precisely because they have the power to destroy everything.
