I'm a newcomer, and my writing isn't very good, so please bear with me.
The transmigrator Wu Liang got a System and transmigrated to another world. After laying low for several thousand years, he was summoned by the people of another world to become a hero. He then kept a low profile for another 700 years, only stepping in when the Demon King reached his doorstep. After defeating the Demon King, he slept in the Demon King's castle for 300 years and became the new Demon King.
When Wu Liang woke up, he was pulled into a chat group, and the story begins.
I'm putting updates on hold for now to revise the chapters. I'll post all the chapters missed during the revision period once it's done. I can only delete three chapters a day, so please bear with me.