Full Metal Panic!

Sousuke Sagara, a seventeen year old military specialist working for the secret organization MITHRIL, has been assigned to protect the latest "Whispered" candidate Kaname Chidori. To complete this task Sousuke will have to deal with enemies from his past as well as the occasional panty thief. Unfortunately for Sousuke, the toughest part of his mission isn't only protecting Miss Chidori but also getting used to living an average High School students life, no easy task for someone raised on the battlefield.
(Source: Anime News Network)