Spring Green

Like rilina says, he's the master strategist of the book. He's also a bit of a trickster character and pretty famous in Chinese literature/culture for being smart and crafty, sort of like Ulysses. The one story I remember the most about him from school is one in which his side ran out of arrows and he constructed these straw men in armor. The enemy shot at them, and they took down all the straw men and collected the arrows in the end.