In episode 147, Yaga was certified as a special class jutsu master.
Using his magic formula, there is a danger that he can create an endless army.
That’s why the Sorcery College certified him as a special class.

©芥見下々/集英社・呪術廻戦製作委員
There were now a total of 5 Special Grade Sorcerers.
But how is a special grade chosen? Cursed Energy?
Pure strength?
There’s another big factor.
It’s “Infinity”.
< 5 Special Grade Sorcerers>
Satoru Gojo → Cursed Technique is “Limitless”
Suguru Geto → Can use techniques with no limits
Yuta Okkotsu → Endless Cursed Energy
Yuki Tsukumo → ???
Masamichi Yaga → Infinite army
They all have characteristics related to infinity.
Yuki’s Technique has not been revealed yet, but her name has a hint.
Let’s look at them one by one.
・Satoru Gojo

©芥見下々/集英社・呪術廻戦製作委員
As Gojo says, his Cursed Technique is about infinity.
Which is like the convergent of an infinite series.
He literally has “Infinity”!!
・Suguru Geto

©芥見下々/集英社・呪術廻戦製作委員
Geto can use Cursed Technique with no limits.
Because he can extract techniques with Uzumaki.
When Cursed Spirits of semi-grade 1 or higher are used…
This means he can use as many techniques as he wants😱
This is also “Infinity”!!
・Yuta Okkotsu

©芥見下々/集英社・呪術廻戦製作委員
Yuta has Endless Cursed Energy.
This is the power of Rika Orimoto.
Which is the result having to detain her soul.
And Yuta became a Special Grade when she was with him.
Actually after dissolving Rika, Yuta became a 4th Grade.
This is information from the Fanbook.
This means that if he loses his “infinity”, he is no longer a Special Grade.
・Yuki Tsukumo

©芥見下々/集英社・呪術廻戦製作委員
Yuki Tsukumo’s powers haven’t been revealed yet.
But there is a hint in her name.
Her name “Tsukumo” means “many” in Japanese.
Maybe she also has “infinity” somehow!!
・Masamichi Yaga

©芥見下々/集英社・呪術廻戦製作委員
And Yaga can create Panda.
If he can create them intentionally, that means he can make an army unlimitedly.
Jujutsu High found out that Yaga had infinity, so they certified him as a Special Grade.
I guess this is the requirement to become a Special Grade Sorcerer.
If there are any characters with this “infinity” in the future, they may become Special Grade…
We all know how special they are.
I think that rule, and the reason for it, will be important in future stories.
Based on the information we have so far, I believe the key word is “infinity.”
What do you guys think?
One thing I can say for sure, I’ll have to go back and read the manga.
And let’s keep checking it!!