It's completely impossible to say Zhang Yu wasn't tempted by Yin Jiurao's offer of 30 spirit coins.
But to let him completely trust in selling it... he couldn't do that either.
"After all, a divine spirit root is of great importance. If anything goes wrong, it would be a big problem."
So the first thing Zhang Yu thought of was Bai Zhenzhen.
That night, during their usual conversation, Zhang Yu casually asked, "Azhen, if you hadn't exposed your divine spirit root back then, do you think you would have exposed it after reaching the second level?"
Bai Zhenzhen replied nonchalantly, "Probably not..."
Thus, through Zhang Yu's intentional probing, he confirmed once again the powerful concealment ability of Bai Zhenzhen's divine spirit root, which is not detectable through ordinary physical examinations.
However, the enhancements the divine spirit root brings to the body are quite real, so the various changes on the flesh due to the divine spirit root can't be completely hidden.
