It's a long story, but in truth, all of this happened in the blink of an eye, from Jiang Xinyun's escape to Yang Fei suppressing Su Jingshu, it only took a few breaths in total.
After dealing with Su Jingshu, Yang Fei quickly pursued in the direction Jiang Xinyun fled.
Just like the last time he was worried about the Mu Family expert escaping, the same reasoning applies. Jiang Xinyun is a core disciple of Wangxian Sect; if she escapes, it would spell endless trouble for him.
At least now he has to search around the Southern Domain World for Tong Yunshu and Qin Yanyang. If his identity and whereabouts are exposed, attracting the pursuit of Wangxian Sect, then it will be troublesome and might even bring disaster to Qin Yanyang and Tong Yunshu.
