The Dream-Wielder of Justice

Every night, I have the same dream. An unknown monster hunts me, and I’m killed the same way every night...

One day, I woke up to find a strange new gas in the world. It could greatly increase my strength, but the monster from my dreams snuffed out my hope.

As expected, I died, killed by my own weakness. But I wasn’t entirely dead, since I went on living in another form. Those monsters want me to help them kill people.