Given the following context:

After thief Alex Cardo gets caught and betrayed by his partner in crime John while stealing an ancient Jian in Thailand, he soon finds himself imprisoned and beaten. One of the guards, Demon, is particularly upset by Alex's appearance and tortures him whenever he gets the opportunity. Alex finds one friend and mentor in the jailhouse, Master Sun, who teaches him a superior fighting style called "Iron Hand". When a "best of the best kumite" is to take place, Demon gets an invitation. Now Master Sun and Alex need to find a way to let Alex take part in the kumite, too.
The final fight pits Alex and Demon together.  At first, and for a long time, Demon has the upper hand in terms of strength and fighting ability.  When Alex is down, he takes one last look at Master Sun and uses the "Iron Hand" against his opponent, severely damaging and defeating Demon.  Alex is the winner, and as part of deals previously made, Master Sun is freed from prison, and so is Alex.

answer the following question:

What is the name of the person against whom Alex uses the Iron Hand? 

Demon