I signed in to the Sunflower Collection at the beginning, and I threw it away

Xu Ling traveled through the fantasy world and awakened the strongest sign-in system in the current version.
[The host signs in for the first time and gets the Sunflower Book]
Xu Ling:? ? ?
System, you seem to have that serious illness!
Can you do some Yangjian exercises?
Sunflower Book?I don't practice!And threw it away, hey, I was just playing!
……
Unexpectedly, the "Sunflower Treasure" was accidentally picked up by another disciple.
Ten years later, the disciple turned into a demon lord, wielding millions of demon soldiers, sweeping towards him, intending to slaughter the world.
Xu Ling, who was drinking tea leisurely in the back mountain, raised his eyelids: "It's you, kid, who picked up that trash book?"...