Ok, guys, listen up, i finally did this on lvl 89 with 50k power.

Ninja Exam 134

Iruka x x
Main Torune x
Akatsuchi x x

3-2-3-3-2 and Dog of Hell

1st round: Wait for Ao to acu Iruka, and Iruka has to avoid it. Then trigger Main mystery.
Torune's clone should live to stop Cho's madness - thats why Akatsuchi and Iruka buff him.
Torune should trigger combo on water main clone, and it should die. Then main kills Cho, and
gets some hp from main. All must survive 1st round.

2nd round: Since Iruka is not acu, target water main with him to stop him using heal mystery,
and use Torune mystery. Now main has to die, take some health from Ao, and Akatsuchi
can be dead, but not others.

3rd round: Torune can die, but Main must survive to to kill Ao and halve hp from Mei.

4th round: Main must survive Mei and kill her - mystery would be great to use, if not acu by
Mei, enough is to survive her attack. If not, pray that Iruka finishes her.

ITS HELL TO DO IT! I needed like 50 tries, Akatsuchi 3* had +25% res on gold +3, and Iruka 2* too on red +2. Torune 3* had life +5% on gold.
Advice - get as much power as u can - more stars, more awakening, at least 25% wherever u can. It took a lot of luck for me, if u have better
awakenings and power on those, maybe it will go easier for you. Cheers!

https://www.youtube.com/watch?v=oXqzIDFitv8 i used this