Deep in the countryside, a man named Okina works as a bamboo cutter in a forest, chopping away at the hollow plants day after day. One day, he discovers a small baby inside a glowing shoot. He immediately takes her home, convinced that she is a princess sent to Earth as a divine blessing from heaven. Okina and his wife Ouna take it upon themselves to raise the infant as their own, watching over her as she quickly grows into an energetic young girl. Given the name Kaguya, she fits right in with the village she has come to call home, going on adventures with the other children and enjoying what youth has to offer.

But when Okina finds a large fortune of gold and treasure in the forest, Kaguya's life is completely changed. Believing this to be yet another gift from heaven, he takes it upon himself to turn his daughter into a real princess using the wealth he has just obtained, relocating the family to a mansion in the capital. As she leaves her friends behind to enter into an unwanted life of royalty, Kaguya's origins and purpose slowly come to light.

Sergeant Sousuke Sagara returns to Jindai High School to protect the precious war asset, Kaname Chidori, from any threat. However, his lack of social skills and real-life experience result in comical yet dangerous situations, endangering the peaceful school life Kaname longs for. As Sousuke continues to bring a wide range of weapons to school as a means to solve threats—real or fake—Kaname struggles to fulfill her duty as the student council vice president all while keeping him in check. To ensure a successful mission, Sousuke is occasionally forced to use the costume of a famous amusement park mascot called Bonta-kun. With his technical expertise, he eventually transforms the exuberant uniform into a cutting-edge exoskeleton that has only one dysfunction: the voice translator can only produce the sound "mofu." Full Metal Panic? Fumoffu depicts the adventures of Kaname and Sousuke as they try to live their normal school lives despite the chaos they inadvertently cause. [Written by MAL Rewrite]

Prequel to

Sakamichi Onoda is a cheerful otaku looking to join his new school's anime club, eager to finally make some friends. Unfortunately, the club has been disbanded and he takes it upon himself to revive it by finding students who are willing to join. Without much luck, Onoda decides to make a round trip to Akihabara on his old, bulky city bicycle, a weekly 90-kilometer ride he has been completing since fourth grade. This is when he meets fellow first year student, Shunsuke Imaizumi, a determined cyclist who is using the school's steep incline for practice. Surprised by Onoda's ability to climb the hill with his specific type of bicycle, Imaizumi challenges him to a race, with the proposition of joining the anime club should Onoda win. And thus begins the young boy's first foray into the world of high school bicycle racing! [Written by MAL Rewrite]