The specific principles of this process are still unknown.
However, after Ezaki Kazu was replaced, although Ezaki Nagayasu noticed something was amiss, neither he nor his relatives mentioned that Ezaki Kazu had ever disappeared.
So it's reasonable to speculate that this process should be relatively quick.
There's no need to really stay underground for years like a cicada nymph.
Furthermore, Kamiyagawa and his team now suspect that the impersonator was drawn to Ezaki Nagayasu due to some folklore investigation he had conducted, leading to the replacement of his wife.
Subsequently, it's highly likely that the impersonator handled all of Ezaki Nagayasu's research materials.
But strangely, Ezaki Kazu was still left in the underground of their house.
Even if that underground space isn't easily discovered, leaving Ezaki Kazu's corpse holds no benefit for the impersonator.
Why did it do this?
It's unclear.
