The moment he entered, the light that came from the other room slowly dissipated. The lights went on narrow and narrow until there was no more light to shed. The room was dark and empty. The floor was concrete. The smell was burning metal. There was nothing but an empty void. Saitama couldn't see himself. His eyes were blinded by darkness. It was only a matter of time before it consumed him.
"Isn't it amazing?"
A voice, deep as the ocean and loud as a thunder, echoed through that dark room. Saitama twitched his head left and right, back and forth, all to find out where the source of voice came from, but he couldn't. All he could see was a dark void.
"The dark room," Target said. "Dark continuous abyss where you cannot tell where you can go, where you cannot see, it's a wonderful place."
"Yeah, wonderful place." Saitama said. "This is where you're going to hide yourself again and again. You're a coward, Target! Face me right now!"
"Do I have to?" Target said. "You're boring me, Saitama. You're the so-called One Punch Man, the Caped Baldy, the Ultimate Hero, but unfortunately you're not a hero. You asked me to fight you, but you don't ask me to stop killing innocents."
"Are you going to do all of that just to prove a point? Is this point that you're trying to make is that I'm not a hero?" Saitama said. "Fine then! I'm not a hero. I can protect myself, but I can't protect everybody. There. You made your point. So stop all of this right now!"
"Do you think that would ever stop me?" Target said. "I'm your biggest enemy. I cannot be seen. You cannot punch me. I'm invisible. I cannot be killed because I'm smart enough to not come near your vicinity."
"You're a coward."
"There's no point of-"
"YOU'RE A COWARD! Saitama shouted. "COWARD! COWARD! COWARD! COWARD! SHOW YOURSELF NOW YOU FUCKING COWARD!"
That's where he appeared... right behind him.
Saitama noticed him in a flash of a second. He also stepped in right in front of him and unleashed his biggest punch yet. His punch was filled with the anger and the spirit of those that he has killed. He swung it right towards him with a hard fearsome grunt.
The punch was strong enough to blow out one side of that entire dark room out, leaving a large gaping hole in it. What's beyond the hole was a dark sky of Y-City. The Blue Moon was shining today and it's enough to illuminate the darkness. He was on a building at least five floors above. The shockwave of his punch was enough to not only blow out that particular part of the dark room, but breaking through every building in the vicinity.
Saitama recollected his vision and thoughts. That's where he realized that he just punched absolutely nothing, and that the real monster wasn't even there.
"There is a monster inside of you."
Saitama didn't waste any time and turned himself around, delivering another punch. It wasn't as strong as the last time, but it was still enough to blow off another side of the room. The shockwave was nothing less devastating, but Target was once again a lot faster than him.
"One that can grow into pure destruction."
Saitama listened to that voice again and did the exact same thing. He turned and punched on Target, but again what it did was just to blow off another side of the room and giving in even more destruction.
"There's no use for another punch." Target said. "It won't work. It will never work."
Saitama turned around and noticed Target himself. The coward was again wearing a very stylish business suit. His face was covered in a sniper crosshair. His hair was dark, stylish, and spiky. It reminded him of where he actually used to have a hair. His eyes were made off of two squares. His mouth again consisted of range measurement and it looked like his mouth was being sewn off. All of that was a crosshair because get it? Target? It irritated him to think about that again and again.
"How..." Saitama said. "How can you avoid me?"
"Hologram." Target said. "All this time, you were punching nothing. You might have the biggest speed, but you will never get a hit on me."
"Stop it!" Saitama shouted. "Come in here you coward! Come and fight me!"
"No." Target said. "If you want to end me, you need to find me Saitama. And you won't ever find me, unless if you prove yourself to be worthy of finding me, just by then I'll let you to come here."
"I will find you." Saitama said. "I swear to god I will find you. If you come in here and destroy my city again, I'll make sure that you leave this world in pieces."
"I cannot wait for that."
That's when Target's hologram completely dissipated. He couldn't touch him anymore. He couldn't interact with him. All that was left was a building completely destroyed on all sides, an environment and destruction that he himself caused on a city that he swore to protect, at least what was left of it.
If there's one lesson that Saitama learned throughout this mindless battle, is that it's better to deal with enemies that you can punch, rather than enemies that you can't.