Who is Zheng Tiancheng?

"Director Sean, do you know what you are talking about?!"
Zheng Tiancheng looked at Lumina Sean who had a calm face, and finally he could no longer control his emotions and anger. His face turned completely dark and his voice became stern.
"I am in good mental health now, have no history of mental illness, and have not taken any psychiatric drugs, so I know exactly what I am talking about."
Lumina Sean looked at Zheng Tiancheng calmly.
"Director Sean, do you think that threatening...