Tells the same story as Full Metal Panic Second Raid and is as such, also based on the novels The End Of Day By Day. Leaving off after the original series, this series tells of Sousuke and Mithril as they fight Amalgam. Like the original series, but both sides have gotten a bit more aggressive...

Full Metal Panic! Sigma was published in English by Chuang Yi Publishing. The series was also published in Brazilian Portuguese by Panini Comics under the Planet Manga imprint from May 2008 to February 2010, which was dropped after volume 9.