Beast: Baku (lion-dogs), Tanuki (raccoon dogs), Usagi (rabbits), high force: Byakko (Lion guardian)
Air: Karasu Tengu (half man/half crow harbingers of war), Yamabushi Tengu (Half man/half crow monks with long noses), High Force: Sieryu (wind Dragon)
Water: Kappa (shelled water spirits), Yuki-onna (frost woman), High Force: Genbu (Tortoise guardian)
Man: Any warrior or monk. Mirrors or other pieces of furniture would make good representations as well. High Force: Well known figures from history; any of the three legendary relics of japan (The Celestial Mirror, Kusanagi, Yasakani no Magatama)
Plant: Bamboo or Azaleas are popular in many areas. Sakura trees are important in Japan, and at high force, a giant oak with strings tied on the branches, and paper seals might be appropriate. The tree on this card is what I mean.
http://gatherer.wizards.com/Pages/Card/Det...tiverseid=75305