[Fukuda has been quiet so far, mostly because Jon's been doing the bulk of the work and obviously this is like, his Job. Even if Fukuda had found something he wouldn't have shared it unless directly asked because that would be rude obviously? But with them frustrated and out of ideas, he finally deigns to speak;]

I don't know how much of a record there is here, but we could see if there's any analogues in the mythology from my version of Japan? Since this Jigoku is so similar to it. It could have some clues.