Passers-By from the Heavens

[New book starts] I once worked for Boss Bai in the world of "Spirit Cage"; I once drove the King of Riders in the world of "King of the Blade"; I once laughed at the director of the Family Planning Office cleaning up the population in the "Marvel" universe; I once... Who am I? I am an insignificant grain of sand in the sky. I am just a passerby in the world, not the protagonist. The world will still function without you.