From Tekken Zaibatsu Wiki
Ling Xiaoyu was relieved to hear that Heihachi Mishima was still alive. She later learned that Jin Kazama, who had become the head of the Mishima Zaibatsu, was out to eliminate Heihachi. Xiaoyu intended to persuade Jin to stop, but she was unable to approach him due to the Mishima Zaibatsu's military buildup.
The King of Iron Fist Tournament 6 was announced just as the world fell into chaos in the wake of the Mishima Zaibatsu's war declaration.. Xiaoyu decided to enter the event for a chance to make Jin change his evil ways.