Section 1 - Criminal Investigations. Batou and Togusa run into a few of their agents at the end of FAKE FOOD.
Section 2 - Controlled by the MInistry of Health and Welfare, they police any and all matters regarding any illegal testing or experimentation of new biomedical technology or drugs. They *WOULD* be the ones in charge of the Laughing Man incident if not for the fact that they're backed up by the use of micro-machine technology and therefore can't get involved (Have to let a neutral, unbiased 3rd party take care of that.)
Section 3 - Japan's version of the Drug Enforcement Agency.
Section 4 - A squad of Rangers from the Japan Ground Self Defense Force. Encounted at the end of 2nd Gig.
Section 5 - Unknown; never mentioned anywhere in the series.
Section 6 - Intelligence gathering on international crime and terrorism. Have the authority to carry out hits on members of other Sections if they find sufficient evidence to support a crime linked to that person.
Section 7 - Unknown; never mentioned anywhere in the series.
Section 8 - Unknown; never mentioned anywhere in the series.
Section 9 - Cyber-warfare counter-terrorism unit. The blurring of technology and humanity usually means that some form of cyber technology will be involved in almost any crime commited within Japan. Unknown to the public, but most branches of the Government acknowledge them as a Black Ops unit. They're structured more as police officers than military.
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"A SMARTER hitman would have shot first..." - Major Motoko Kusanagi