>>2667264Just going to add a little bit to what this anon said.
The Men in Black work for Tachibana Labs, that's pretty clear from the scene where Lain meets the office worker who questions her about her family. From there was can also assume Tachibana Labs knows quite a bit about everything.
As they should, they are really the starting point of all this; it was there Eiri worked on Protocol 7. Tachibana Labs had also mapped the human genome, which in late 90s scifi basically means they can pretty much create life.
Eiri put his own consciousness into protocol 7, and killed himself. From the wired he manipulated the knights into existence, so that he could merge the two worlds and become God.
I don't have much to back it up other than the mapping of the human genome, but I think Lain had always existed on the wired, but didn't have any sense of self without a body. In order to combat Eiri's plan I think Tachibana uploaded her into an artificial body so she could develop an ego and hopefully decide to stop Eiri.
Lains family were probably just assigned as caretakers, and the Men In Black exist to both combat the knights and possibly Lain.
