Blame! 1 - tsutomu nihei

In a future version of Earth, there is a city grown so chaotically massive that its inhabitants no longer recall what land is.

Within this megastructure the silent, stoic Kyrii is on a mission to find the Net Terminal Gene--a genetic mutation that once allowed humans to access the cybernetic NetSphere.

Armed with a powerful Graviton Beam Emitter, Kyrii fends off waves of attacks from fellow humans, cyborgs and silicon-based lifeforms.

Along the way, he encounters a highly-skilled scientist whose body has deteriorated from a lengthy imprisonment who promises to help Kyrii find the Net Terminal Gene, once she settles a score for herself.