The empty comment makes Japan frown in realization. It is. He personally doesn't find it so strange, but he's used to staying in his home alone (so he thinks) so it's a similar sort of feeling that it brings rather than 'creepy.'

However, considering the circumstances, this was creepy. Yes.

"And quite large..." Japan seems more worried about getting lost in this place, as he glances back from where they came. Although, how lost can they get if they already have no idea where they are?

"There were many others in the same position as us," he recalls from the medbay. "But I am not sure that that is such a comfort." But his troubled expression shows just how much he wished things were more clear.