Long time ago,the world is separated by a border.This border is created by the 10 person who were called the CONQUERORS.They are the humanity strongest warriors.This border is built for a reason and that is because the Demon Lord.The Demon lord and his army is unstoppable.The human and demons would fight for eternity until these 10 Conquerors defeat him and create the border.But that was several hundred years ago.In 2030,a guy named Haku,the first "Leader of Conqueror" make a pact with all demons and the current Demon Lord.He asked for what seem to be impossible,a harmony pact with the demons.No one would ever think to make these pact because the demons loves to fight and kill and destroy everything but Haku made it possible to live peacefully with the demons.This pact has been going on till now.In 2050,demons and humans still live together and building a peaceful world.Until one day,a person called Zan was born.Zan is the first person that was born from a combination of demon and human.His father is Haku,"Leader of Conqueror" and his mother is just some ordinary demon that Haku fell in love with.Ever since he was born,the world became what it was long ago.And the war between human and demon takes place again.The reason this war happened is because the human and demon both possess unique skill.The human possess the "LIGHT BRAIN" which is an ability to use their brain to the fullest and the demon possess "THE IMMORTAL" which is the ability to live forever.That's why the current demon lord couldn't let this be because he knows one day Zan would be the strongest human in the world and will one day destroy all of demon's existance.That is all his assumption but the poor innocent baby wouldn't even think of it.He just wants to live a normal life.Since the rumors of his born is the reason of war between human and demon,all of humanity hate and despise him including Haku and his demon mother,Uraraka.All of humanity including the 10 current Conquerors has decided to kill Haku and his whole family.They couldn't win against all of humanity so they ran till the end of the world but still it's very difficult to run from 10 Conquerors eventhough Haku is the Leader of The Conquerors.After a month of running,Uraraka suggest an idea.She suggest that they trap Zan in the "WORLD DOMAIN".This domain can only be cast by X tier sorcerers and Uraraka has what it takes.In the world,there are 5 different class,ASSASIN,SORCERER,WARRIOR,MARKSMAN and KNIGHT.In each of this class they are measured based on ranks,as there tier E,D,C,B,A and X.There are only 10 person whom is tier X at a time.Uraraka summon the World Domain.This domain can trapped a whole country and prevent anyone from entering or leaving it.Uraraka plans to place Zan with all of her and Haku comrades who are willing to take care of Zan in it.This way Zan will be protected by anyone who wants to kill him including the demon lord and the 10 Conquerors.By summoning the World Domain,Uraraka is left with no mana at all.Haku sits beside her and hug her whispering"You did the right thing.I'm sure he will become the strongest man one day.After a few minutes,the ten Conquerors arrive there.Haku last words to them are,"I hope all of you would watch over him to make sure he became the strongest human in the history.All 10 Conquerors bow to Haku and strike a beautiful magic through him and Uraraka as this is the proper way to kill someone with such ranks.15 years have passed since then.Zan has achieved number 1 in middle school in terms of strength,agility and clever.Because of the rapid progression spell that was casted by tier X sorcerer named Megumin,which is the principal of Zan's middle school,the population of people in the World Domain has reached 1.30 million peoples.But only a few of them knows who Zan is really are and that they are actually living in a dome.Even Zan himself don't know who he really is.He lives with Asuka,tier A Warrior and Arthur,tier X knight but Zan didn't know their ranks.To him they are his aunt and uncle who takes care of him since his parent died of a car accident.He was living a peaceful life.Until one day,something breached the dome.It makes a hole from above side of the dome and heading straight to Zan's house like an asteroid then it lands right on Zan's backyard.At that time,Arthur and Asuka are not home.Out of curiosity,Zan carefully walks toward the asteroid.He couldn't believe his eyes.It was a girl.An eight grader girl.She stand up and look straight at Zan."I found you"she said while making a smug face.Zan was clueless so he asked,"who are you??".The girl started laughing hysterically."It's okay your majesty you don't need to know who i am as you are going to die in the next few minutes"then she laugh again."Your majesty??i think you must have taken me in for someone else.I'm just an ordinary guy"Zan replied."That's a pity.I'll just have to tell you everything."And that is the beginning of Zan' tale to become the strongest human.