Takes place in the "near future".

The world now has a virtual space which goes by "Yggdrasil", which is connected to via complex cybernetics. This new development leads to new types of crimes by terrorists. Along with a new wave of drugs which affect the cybernetics.

Shiro is an information specialist and works for the the department or Ministry of Internal Affairs and Communications. His partner and colleague Kisaragi began working on a small case when things take an interesting turn...