I Have Unlimited Upgrades in the Evil World

People's hearts are different, and evil spirits arise on their own. The world is not upright and strange things are rampant. This is a world of cannibalism, a world where demons and evil spirits are rampant. Song Si came through time travel and obtained a system at a critical moment. Any martial arts can be upgraded. The Iron Head Kung Fu, Iron Throat Kung Fu, Iron Crotch Kung Fu, Iron Arm Kung Fu, Iron Leg Kung Fu, plus the Iron Cloth Shirt, can be upgraded to an immortal golden body. The Shadowless Sword Technique, Rapid Rain Sword Technique, and Spirit Snake Sword Technique, plus the Sword Drawing Technique, are upgraded to the Heaven-Destroying Sword Drawing Technique. Fight against evil spirits and draw your sword to slay the sky! Who said that a martial artist who has practiced to the extreme can only make his meat chewier?