FR THO
Yeah, I'm also a little perplexed to this build-up. He isn't mentally mature enough and should have been portrayed more as a teen in puberty than "5" years old because it doesn't make sense. Author should have elaborated rather than making it vague.
The little bits of flashbacks are inferring that they're either Sui's forgotten memories or Zashiki's old memories, but if they really did seal him at a young age, yikes. No idea how old he really is, but probably a minor, but not young enough to be child level.
Since yokai is immortal, he could already be living for hundreds of years already.
But mentally, he'll always be 5 - 6 yrs old.
That's what zashikiwarashi is. They inhabit the house by playing and doing harmless pranks, and along their stay, they give luck to the home. That's their purpose. No-one mature with a teen or adult-like mind would want to play children's game all the time they're awake.
It doesn't sit well with me too, but sadly, that's how it is.
Uhhhh can you please confirm he isn’t actually mentally 5 yrs old before we start the activities