The legendary mortal sho

Briefly about The legendary mortal sho manga:

Zhang Gong is a little herbalist on Mount Shu. One day, he went to the mountain for picking herbs and met an immortal who was beheading a monster. He was accidentally drawn into a big fight between monsters and demons. After a soul-stirring adventure, he found his real origin, and then involved in the turbulence and fights among the three worlds