Fruits basket is a manga series. Fruba is mostly about the Chinese Zodiac.  Most of the main characters are possessed by the vengeful spirits of the zodiac animals. If you count the cat the zodiac contains 13 animals. Their spirits are all very different and the cat is shunned, or in other words not aloud with the others of the zodiac. Another interesting fact is the zodiac members transform into there animals spirit when they are hugged by the opposite gender.