@Nakanowatari It's normally the opposite, Japanese construction tends to be very poorly soundproofed, especially in apartments. That they normally cannot hear each other's livestream shenanigans, especially when one is singing and another is being an overly dramatic hardcore chuuni, would imply they've either: all done extra soundproofing themselves; or the building was already specially constructed to be better insulated and these kids were all deliberately gathered in this place for a yet to be disclosed purpose. The latter presently seems more likely considering we also know the common areas of the house are lined with cameras, being monitored by a yet to be known party.