Now that I think about it, after HM, what else did we miss?

Zi (子): The Rat > Nazrin and Byakuren
Chou (丑): The Ox > Keine
Yin (寅): The Tiger > Shou
Mao (卯): The Rabbit > Udongein, Tewi, Reisen II
Chen (辰): The Dragon > Meiling, Iku, Kasen
Si (巳): The Snake > Kanako, Mishaguji
Wu (午): The Horse > Nue? unless Satsuki is Kirin
Wei (未): The Sheep > Nothing really, but the closest one is Maribel or Mokosheep and Byakusheep
Shen (申): The Monkey > Ichirin
You (酉): The Rooster > Futo(thanks, Mami), Mokou
Xu (戌): The Dog > Kyouko, Momiji, Kagerou, Sakuya
Hai (亥): The Pig > Nothing comes off my head for now

Pig ==> sin sacks

Nue is like a wild card. She'll be anything needed

Well, if we want to go with the obvious for the pig, there is a certain ghostly glutton.

Or we go with the whole story of the pig and how he was the last to arrive because he was hungry and fell asleep.