Prologue

                                    

                                          
Seven years ago in Japan in the Woods
Unknown two people are into sparing training, one is in his adult age male in all red-ten color, with armor, some knifes on each his ribcage, & a katana on his back, the way he stand like he never had any sleep in his life.
Face to face to tried, cuts, & bruises, nine year kid, a boy with black curved hair, both sliver eyes, catching his breath, looking at his mentor, the Hero Killer: Stain.
Stain: "That's enough for today, heal up & rest. You'll need it"
When he about to walk away, the kid say,
Boy: "No... I'll keep up, Sensei... I can do this...all day..." *standing up & stand in his fighting pose*
But Stain pull his katana & pointed at the kid's face & says to him,
Stain: "And your dead. Listen & remember this, never underestimated your foes, it doesn't matter who your facing in battle! To win & defeat your enemy you must know them, both strength & weakness. Especially they weakness, explore those weaknesses & use it against them. Same thing I did to you just now, both of your weakness & downfall. Do I make myself clear, Kage Tatsuma?
The boy who known as Kage falls to his knees still catching his breath & says to Stain,
Kage: "Yes...sensei..."
Time skip to seven years later, at night in Japan:
A unknown thug running into the allyway, scar in fear for his life, the thug find the place to hide from whoever is after him
Few mins to catch his breath until he hear the voice that made him shock in cold fear to the core when the voice say to him in his ear,
???: "Did you really think you got away from me, Kolyat? No one is save & there is no escape from the shadow not even you."
Everything went into black only hear the man screaming in horror when the unknown figure slit his throat & stabbing the thug in the chest by saying to thug's eat in his dying breath.
???: "Go. To. Sleep."
Three mins later:
The cops shows up, found the body, & feel disgusted, one of the cop say,
Cop 1: "Nightslasher." *another cop says*
Cop 2: *sign* "This won't never stop will it?
From up top of the roof when we see the one who called by as Nightslasher is watching & walks off by answering the cops question,
Nightslasher: "No. I'll never stop until I give everyone what they want, true justice, peace, & freedom."
Until a voice says to Nightslasher from behind him,
???: "By killing villains, criminals, & thugs? Is that what they want?"
Nightslasher turned around & sees a pro hero, in all black, long black hair, grey robe around his neck, & yellow goggle.
Nightslasher: *whispered* "Ah shit. Eraserhead."
He was about run off but Eraserhead catch him by using hisskated, Nightslasher try to fight back to break free, & try to use his quirk but couldn't.