He must keep his promise, find a way to let civilization endure eternally, or else he'd only waste his true friend's sacrifice.
...Oh, there's one more thing.
In the eyes of the high-dimensional beings, time isn't time, space isn't space, and perhaps death is not absolute... maybe he can find a way to bring his true friend back to life.
Following causality, he climbed, paying the price of endless time, and managed to obtain the "cause"—"Yasa Acto's" cause. He buried this "cause" in his small world. Then, he embarked on a journey into the depths of the universe, searching for a method to alter the causality of death.
This is nothing more than a wild imagination, uncertain of its practicality, but there was no other way.
Besides, there were many other people he wished to resurrect.
Tretiya, Lin Guang, Beili Sier... and other possibilities like Su Ming'an, Lv Shu, Yuanyuan... He gradually found their incomplete "causes," bit by bit burying them in this "New World."
