A ghost and a human.

Sokka: So you thought about that? 

Leo: Yes I thought a lot, and my answer is ...... Yes ... 

Sokka: Okay, now let's sign the contract.

A very large sheet appears, to sign the contract had to be cut on the finger and blood flowed over the sheet, and the ghost had to keep the sheet until, will die or until the master dies. 

Sokka: Now a contract has been officially signed between a man and a ghost.

Leo: ..... now what are we going to do .. 

Sokka: I need you to check some documents about a certain man, I'm a ghost, I don't know how to do that, that man could be the killer, only this time, I want to know for sure, before I kill. 

Leo: Okay, as you say. 

Sokka and Leo go together to the house where he found the documents, the house was in a forest, far from Tokyo and so he had to drive, when he reached the house in the forest, both the house and the trees next to it were on fire, officially the forest was on fire, Leo wants to call the fire department, but something interrupts him, namely the fact that Sokka put out all the fire, using a technique and said: 

Sokka: Reverse technique! 

Then he shouted: 

Sokka: Show yourself, I know you're there !!! 

Suddenly a ghost twice as tall as Sokka appears in front of Sokaa. 

* AUTHOURS NOTES- GHOSTS LOOKED EXACTLY LIKE PEOPLE, JUST BECAUSE PEOPLE DIDN'T SEE THEM, THERE'S NO DIFFERENCE IN APERRANCES * 

Sokka: Who are you ? 

Ghost(Joester): Im The Ghost of Souls.

Sokka: I will exterminate you, if you set fire again, you have already made the 15th incident, you are going to burn all of Tokyo ?

Joester: Yes, do you mind? 

Sokka:In that house there were some documents about a certain crime, which I have been following for 14 years !! 

Joester: Not my problem !!

Suddenly Sokka attacks Joester with an attack, which was in the shape of a round ball, but Joester avoids him and runs away! 

Joester in his mind: I don't need to fight him, now, I fight at the end, when I finish the plan, he's Unhappy Kid, he's the ghost, who's out of rank with me, I risk being exterminated, if he's stronger !

But Sokka doesn't go after Joester either, but he goes down to Leo and says: 

Sokka: He is the ghost who is on a level with me, as he was arrogant, he would have fought, but he did not fight, which means he does not want to risk! 

Leo: Doesn't he want to risk doing something? 

Sokka: Probably.

Yana, meanwhile, was at the academy, even though she has a contract with Joester, she can't give up her dream of killing ghosts. 

Joester teleports to Yana and tells her: 

Joester: If you need the strength to graduate from the academy, then I'll give you a thousand people. 

Yana in his mind: Is it that strong? 

Yana: No, Thanks, I can handle.

Then Joester disappears. 

Mirai calls some old friends in a group. 

Mirai: Hi, you have to come to Japan, to Tokyo, I caught the so-called Ghost Demon, but already Tokyo if it continues to burn every day, then Japan will run out of capital, it's a ghost in the middle, but I do not know which.

Friend 1: I'll be there in 3 days 

Friend 2: I am in Moldova, it will take some time to get to Tokyo, but I will arrive soon !

Who are these friends?