When "Zero" woke up on the beach of an unknown island, he lost all his memory, and all that was left in the world was the cage in front of him surrounded by a gray ocean. This sea is not an ordinary sea water, but a "forgotten sea" that is constantly eroding the island and devouring everything. The only building on the island is a lonely white lighthouse, which seems to hide the secret of his identity. In order to fight against forgetfulness and find himself, "Zero" must go deep into the lighthouse and discover the "memory anchors" buried by his own hands. However, every flashback of memories is accompanied by tearing pain and a storm that can destroy the entire island. He gradually discovered that this isolated island might be the last barrier of his consciousness, and his biggest enemy was the self that longed to be forgotten.
