Tengen's defining trait was that his barrier techniques were the best in the world.
Tengen's barriers covered all of Japan. Almost nothing that happened within them could be hidden from him.
He could practically be called omniscient.
But what did this omniscient Tengen do in the original story?
He neither told Jujutsu High about Sukuna's resurrection.
Nor did he tell them about the Culling Game.
One had to understand that Kenjaku's Culling Game plan had not been arranged over merely ten or twenty years.
It had been laid out bit by bit over thousands of years.
Such a long period of time, such a vast range of activity.
Could Tengen truly have known nothing?
It was impossible just to think about it.
Yet what was the result? He said nothing.
He simply cooperated with Kenjaku in launching the Culling Game.
Furthermore, in the original story, he had directly gotten Yuki Tsukumo killed.
It was understandable if others did not know about an Open Domain.
But as an existence who had lived for over a thousand years and came from the same era as Kenjaku and Sukuna.
Could Tengen not have known what an Open Domain was?
And it was not as if Kenjaku had never used Domain Expansion during those thousand-plus years.
As long as he had used it, Tengen would inevitably have seen it.
He knew Tengen's domain was open.
Yet had Tengen mentioned such a crucial detail?
Not only had he failed to mention it, he had even coaxed Yuki Tsukumo into giving up on expanding her own domain to counter Kenjaku's Domain Expansion.
In the end, this directly led to Yuki Tsukumo's death.
Given Tengen's performance, it was hard to call him a good person.
It would not be excessive to say he was Kenjaku's mole planted