Full Metal Panic! Another

A high school student named Ichinose Tatsuya lives with his father and younger sister, working occasionally with his father's business, which involves operating a Power Slave. He has a pattern of becoming infatuated with foreign women, with little success. While in the mountains, he encounters a foreign woman named Adelina, who is accompanied by a military Arm Slave named "Shadow." Intrigued by her presence and weaponry, Tatsuya becomes involved in uncovering the reasons behind her appearance in the mountains.