Mia Yung is the youngest member of the gang.
Mia, who is only 18 years old, lives with her father in a staging post somewhere in the mountains near the Mexican border. Previously this station had belonged to the Pony Express, but now riders seldom pass through this inhospitable barren region. Despite her young age, Mia is already an experienced and courageous fighter and has the heart of a lion. Her only friend is a small monkey called Mr. Leone, which she has trained and which obeys her every word.
Mia’s standard weapon is a one shot blow pipe that shoots poisonous darts. Any enemy hit by it succumbs to hallucinations within seconds and begins to fire in all directions like a madman. She can lure enemies by blowing through her whistle. She can also lure an enemy with her pet Mr. Leone by setting him directly to leap at the enemy’s throat or distract enemies by sending him to a chosen pile of peanuts where he dances around. By throwing a fire cracker she can blind a whole group of opponents at once. Being small and agile, she can hide in a empty water barrel and can run faster than everyone in Cooper's gang.