Following the success of the Dawn Rebellion, Degwin negotiates with Vice Admiral Revil to surrender all Federation assets and the complete withdrawal of Federation forces from Side 3 to prevent similar incidents from happening again. After bring reprimanded by Degwin for failure to look after Garma, Dozle sends Char - who motivated Garma into starting the rebellion - to Earth; in response, Char requests to become a mobile suit pilot when he returns. Feeling the burden of his responsibilities, Dozle proposes to cadet Zenna Mia. In the Earth city of Manaus, Char lands a job as a mobile worker pilot at a construction site. He meets a young Lalah Sune at a casino.

Motoko and Batou work to try to stop a terrorist organization whose symbol is the Scylla. Meanwhile, Togusa investigates a murder of a man who possessed a prosthetic leg manufactured by the Mermaid's Leg corporation.

In this prequel set one year after the fourth World War, cyborg and hacker extraordinaire Motoko Kusanagi from the military's 501st Secret Unit finds herself wrapped up in the investigation of a devastating bombing.

Freed of her responsibilities with the 501 Organization, Motoko Kusanagi must now learn how to take orders from Aramaki. Someone hacks the Logicomas, and Batou enlists the help of former army intelligence officer Ishikawa and former air artillery expert Borma. Kusanagi also seeks to enlist ace sniper Saito and undercover cop Paz into the new Public Security Section 9.

The anime's story is set in 2027, one year after the end of the fourth non-nuclear war. New Port City is still reeling from the war's aftermath when it suffers a bombing caused by a self-propelled mine. Then, a military member implicated in arms-dealing bribes is gunned down. During the investigation, Public Security Section's Daisuke Aramaki encounters Motoko Kusanagi, the cyborg wizard-level hacker assigned to the military's 501st Secret Unit. Batou, a man with the "eye that does not sleep," suspects that Kusanagi is the one behind the bombing. The Niihama Prefectural Police detective Togusa is pursuing his own dual cases of the shooting death and a prostitute's murder. Motoko herself is being watched by the 501st Secret Unit's head Kurutsu and cyborg agents. Written by Jiilo_Kim