Prologue of Blame!: Sanakan

In the post-apocalyptic future, the complex networks of machines have created chaos and the human world was destroyed. The robots known as the "Constructer" continued to build a meaningless structure with no one to guide them. Soon these cities reach out to the outer planets and another breed of life form emerges. Follow the journey of a strange man, name Killy, in his search for the understanding of the chaotic world being run by Silicon lifeforms out to destroy him and every living thing in their path. (from manga)