The Favor Debt Repayment System: From the Richest Man to a Demon

[Revenge + no female lead + System + ruthless and decisive] The transmigration System never showed up, and even in old age he was poisoned by his unfilial descendants. Just as he was about to die, the System finally arrived.

The Debt of Gratitude Repayment System lets him collect anything he wants, including money, control over another person's body or mind, and power, as long as that person owes someone a favor.

Tremble, you unfilial descendants!