I really like how good Yamamoto at psycho analyzing someone. He is not your typical shounen MC that fixed someone problem by pure luck, he is trying to fundamentally fix Hayashi issues step by step.
Yamamoto noticed her nonverbal sign of wanting someone to help her in the form of watchlist...
Fuuuucck, this manga so traumatizing.
So.. that's door basically a "mouth" in a shape of a door. It mind controlling whoever entered that door and eat them.
So... why not try with an iron chain instead of just a rope???