>>281649159
I dropped Hikaru after like 10 chapters, so I don't know what its ghost hole is like. But Hanako-kun has one in the domain of the grim reaper dude that leads to the realm of the dead. And Sekiro has one in a cave that technically doesn't lead to the underworld but does lead to a spooky undead village.
I can only assume that something depicted an entrance to Yomi as a hole in the ground at some point and it stuck.
>>281649331
I wonder if there is an unstated factor of them realizing that if it isn't real then performing wouldn't be that big of a deal? Everyone but Kyoya is a monster whose digits would just reattach.