Full Metal Panic! 1st Section: Boy Meets Girl

About two months have passed since the hijacking incident. Sousuke Sagara, a member of the anti-terrorist organization Mithril, continues his undercover high school life while serving as Kaname Chidori’s bodyguard. But one day, a new terrorist group known as A21 begins operating in secret, setting its sights on Tessa, the young female captain of Mithril’s submarine. As the threat grows, Sousuke and his allies find themselves drawn into yet another dangerous conflict.

When Sousuke invites Kaname on what seems like a trip to a tropical island, they instead find themselves aboard the Mithril's submarine. Their journey takes a dangerous turn when Gauron, the terrorist believed to be dead, resurfaces and hijacks the vessel, forcing Sousuke and his allies into a desperate fight for survival.