There's a virus in this system that's somehow managed to be even more insidious than the one Lovers and Devil concocted for the Grid. Affected people don't know they've been infected and end up running around all night Interfacing the code to anyone they can reach.

Claudia-san says she thinks it's a Trojan. [What that means in computer terms, he only knows thanks to her later explanation, but Delaunay's up on his classic literature - if the names of the old places aren't different in his reference, he might be able to guess how it got its name.]