- The existence of Banana Fish itself. This is a drug that causes you bad trips after bad trips, trapping you in a nightmarish and painful version of the world created by your own mind. After Abraham "perfected" it, it was used as a way to brainwash their victims and make them believe that someone specific was the source of their pain and fear, prompting the brainwashed to kill innocent people, of course, even when they manage to assassinate their target, the fear remains and the victim of Banana Fish in their desperation kills themselves. Even if you somehow survive, you are still trapped in your own mind by the effects of the drug and there is no cure.
- Throughout the story, we see several examples of how this works but the most heart wrenching example is of Shorter. We're talking about a character that did everything they could to protect their friends and family, consequences be damned but Banana Fish destroyed them and Ash was forced to kill them before they could fatally harm Eiji
Nightmare Fuel / Banana Fish