What are Holo's roots in Japanese tradition? The rich background of Holo: being a minor deity of harvest, her forms, shapeshifting, powers and limitations, likes and dislikes, traits character etc - how is it grounded in Japanese beliefs, myths, traditions, and legends?

Is her lore entirely made-up for the needs of the show; did the authors take strong artistic license on some more or less common legends; or is she shaped closely after a character well known in Japanese culture?

If it's one of the latter, could you give some sources or summaries of the original upon which she is based?
I wasn't able to find any references that state that the exact background that Horo has originates from some exact legend or myth. However, it is definitely not entirely made-up. Animals play a significant role in Japanese folktales. Two of them are also widely known to be able to transform into humans, and other objects: kitsune (狐) - fox, and tanuki (狸) - raccoon dog. 

Also, the Wikipedia article "Japanese folklore" has this interesting fact:


  Marriages between humans and non-humans (irui konin tan (異類婚姻譚 "tales of heterotype marriages")) comprise a major category or motif in Japanese folklore. Japanese heterotype examples such as the crane story describes a sustained period of married life between the interspecies couple, in contrast to Western examples like Frog Prince or the Leda myth where the supernatural encounter is brief.


I believe we can say that all these definitely have some resemblance with Horo's background.