I was thinking about how strong enemies show up in manga. After them, an even stronger enemy shows up, and after them, an even stronger one... so what happens at the very end? It's kind of like thinking about the edges of the universe. Once you look about the world, you realize that what it really means to be a "strong" person is not to do bad things. "An enemy who does bad things" is a person who has "a spiritual weakness," and what's truly scary is when someone takes that weakness and uses it to lash out against others.