Arahan (2004) on Netflix

Plot summary

Centuries ago a warlord hunted a key that would give its holder power over the world, and the slaughter that followed drove the Tao Master Heuk-woon to kill him and seize the key for himself. The six remaining masters locked him in a dungeon beneath the ground and kept the key between them, waiting for a true Arahan. Now a rookie auxiliary officer named Sang-hwan, laughed at by everyone, chases a purse snatcher and is struck by an energy attack from Wi-jin, a prospective Aruchi. She takes him to the Tao school, where her father Ja-woon and four companions treat his injuries and discover an unusual amount of qi in him. They propose training him, and he accepts.