Dungeons suddenly appeared all over the world.People became "explorers" and entered dungeons to get their hands on resources that could only be obtained there.In order to help his childhood friend who was suffering from an incurable disease, Kurose Sakuto also ventured into dungeons in search of the "elixir," a medicine that can heal everything.However, he was notified by his companions that he was no longer needed.Set in dungeons and the real world, he will face monsters and malicious humans.