The Monkey King is the hero of The Journey to the West and the great disciple of Tang Priest. He went all the way to protect the Tang Priest's Buddhist scriptures in the West, and went through all kinds of hardships on the way, and finally achieved a positive result, which became the battle to defeat the Buddha. 500 years before the Buddhist scriptures, the Monkey King was imprisoned at the foot of Wuxing Mountain, and was punished for making a scene in heaven 500 years ago.
The Monkey King, a thorn in the side, refused to accompany Tang Priest to learn Buddhist scriptures, so Guanyin Bodhisattva put a curse on him. Once the Monkey King was disobedient, and the Tang Priest recited a spell, which gave the Monkey King a splitting headache. Guanyin bodhisattva not only gave him a tight hoop, but also gave him three hairs. In Journey to the West, Guanyin gave Monkey Brother three hairs. Why did Wukong use it once and not use it?
These three hairs really do a lot of work. He can become many doppelgangers to confuse his opponents. At the critical moment, these three hairs can become other treasures. At that time, the Monkey King was put into the cylinder of Yin and Yang. Originally, the Monkey King didn't take the pillars of Yin and Yang seriously, but after a while, he found that the pillars of Yin and Yang were more powerful than the old man's blast furnace, and the burning the Monkey King was very uncomfortable. The feeling be nasty under the Monkey King thought of SAN MAO, so he took out SAN MAO, became the Jin Gangzuan of A Jin, drilled through the bottle of Yin and Yang. But after that, the Monkey King never used the three hairs again.
In fact, this San Mao's role in the Monkey King is not particularly great. At that time, he could completely pierce the yin and yang pillars with one stick, but I didn't expect that in an emergency. The Monkey King's usual monkey avatar can also be completed with ordinary monkey hair, and it is not necessary to use those three hairs. So, it's not that the Monkey King doesn't want to use San Mao, but it's useless. Maybe the Monkey King simply forgot the existence of this San Mao.