Treasure Hunting in a Weird World, I Will Catch the Secrets and Become My Little Brother

Whenever Resurrection Day comes, the mental hospital will open the door to a strange world. In that strange and raging world, the lucky ones can possess terrifying powers. Everything obtained in the strange world can be used in the real world. Some people have found the medicine that can lead to immortality, some have found the secret method that will shock the world forever, and some have gained infinite wealth...