Reincarnated Into The Demon Emperor's Body

MC was transmuted to a cultivation world one day. He became immortal after cultivating for thousands of years. But one day he was killed by Demon Emperor in the immortal Demon Emperor war. Demon Emperor himself killed millions of immortals. After MC died he reincarnated into the Demon Emperor's Body and was able to understand the reason why the Demon Emperor was so powerful. The reason was Demon Emperor's: Demon Emperor System. How Zhu Shi will be able to achieve his goal without being completely evil and avoid the complete massacre of the immortals.