The magical creatures that hailed from the Blessing Of The Ocean pearls were indeed able to detect lies, but their ability was constrained to the present time.
Such, when one would tell a lie about an occurrence in the past, the bird would not be able to make a judgment. Unless of course, the occurrence left its mark in the present time.
Whether or not Zhang Fengxi lay with Liu Wenyuan in the past was irrelevant. If he did, though, he would have left some traces inside Liu Wenyuan's body.
It was a simple question. Yes or no.
Liu Wenyuan curled his fingers under his sleeves. His tense face was directed to the floor.
"This subject is not certain," he thus replied.
Liu Yichen snapped his head in his son's direction in bewilderment.
