The Underworld Agent with a Debt of 1.4 Billion

My name is Zhou Ming, a time traveler who should not exist. I was arrested by the underworld because of being a "black house". There is no my name in the book of life and death in the underworld, but there is a huge bad debt caused by me, involving 1.4 Billion lives. Faced with this mess that gave even the King of Hell a headache, they "generously" gave me a position - Agent of Underworld. The power reaches the heavens, but there are no soldiers or generals. In order to survive, I had to conduct my "business" on earth. Sign a contract with the devil, cooperate with the spirits, turn human lives into chips on the gambling table, and turn the world into a live broadcast show. But I know this is just the beginning. When I finally collected the first "repayment", I discovered that I was already the only "legal heir" of this dead debt.