My Mortal Enemy Is Actually Related to Me by Marriage

Ning Jianghuai knew Yun Zhixi was very strong when he saw her for the first time in a swordsmanship competition, but before they started fighting, something strange suddenly appeared in the sky. Unexpectedly, the Abyss was opened, and demons roamed the world killing people. That guy actually entered the abyss and was never heard from again.