Demon God Subjugation Method

"Tell me again how many years of my life this piece of shit will take me to live?" "Don't worry, it's really amazing how it gets bigger and smaller..." With a "ding dong" sound, Wang Yan, who was sleeping in class, was selected by the system. He and other system owners will form a demon subjugation team to resist the coming four demon gods... Wait! Why did the First Demon God arrive three days later? Too late to talk nonsense? The situation is urgent, undercurrents are surging, and time and space will intertwine to reveal the answer to defeat the devil! [The system will be upgraded. There are a lot of foreshadowings in the first 50 chapters, including elements of time travel]