One Small Detail Everyday. Day 8, The Red−rumped mandril/Red-Buttock Baboon (赤尻马猴) is from Aolai, Mount Huaguo. He's Wukong's Marshal. Chapter 3:猴王将那四个老猴封为健将；将两个赤尻马猴唤做马、流二元帅 knows all about the Yin and the Yang and human affairs, can go into or out of anywhere, and knows how to prolong its life.