Ning was running across the city with a massive sound coming off of him. Wherever he found zombies, he would kill them and take away the Yin Qi from them.
Very soon, he came across a problem. It was night time and natural yin qi was everywhere. He couldn't separate Yin Qi from the Unique Yin Qi.
So every once in a while, he would stop the technique. The Natural Yin Qi would disappear in the atmosphere, while the Unique Yin Qi would just attack his body, rotting it very fast.
He would have to run away each time and gather the Unique yin Qi even further.
"This should be enough," he thought as he started the Sun God's Morning Cleansing technique. Soon, the Unique Yin Qi was destroyed.
Once it was gone, he started going to a different place and doing it again. He didn't know any other way to remove this Unique Yin Qi, so he didn't even bother trying to do anything other than help the people right now.