I question if post #50549 and its children really are supposed to be from Made in Abyss, even it's from the same artists and the characters look pretty similar, simply on the grounds that the image goes back to 2003 while Made In Abyss didn't debut until 2012.
Sure, Tsukushi may have drawn concepts and whatnot prior to that, but I haven't seen anything of the sort on the artist's website.
I could just remove those tags from these posts, but what if I'm wrong?
Maybe someone more versed in Japanese can glean something from the above link and here