In the "Ghostly Field Club" album there is a track called "Strange Bird of the Moon, Illusion of Mysterious Cat", could this picture be a reference to that song maybe?

Soo that’s how their “animal forms” looks like?... I wonder if neither Renko or Merry have any sort of pets, and more importantly, if depending on where do resides (a normal house or an apartment) do they have the stuff to let them have pets in there too?