Yu-Gi-Oh! GX: The Guardian of Duel Academy

AU. Duel Academy, the school built by Seto Kaiba to foster a new generation of talented duelists is one of the greatest institutions in the world... that said, with the knowledge of three dangerous cards sealed under the school it might be a good idea if someone there was able to keep an eye on things and let Kaiba know what's going on at Academy Island. (Full summary at chapter)