Saijaku Muhai no Bahamut

Saijaku Muhai no Bahamut (最弱無敗の神装機竜, Undefeated Bahamut Chronicle) is a 2013 and ongoing light novel series written by Senri Akatsuki and illustrated by Ayumu Kasuga. It was initially released on August 12, 2013, by SB Creative under the GA Bunko imprint. The series received a manga adaption in 2014, written by both Senri Akatsuki and Itsuki Watanabe with illustrations by Fumi Tadauri. The manga was published online in Square Enix's Gangan GA magazine. During the Winter 2016 anime season, Saijaku Muhai no Bahamut received an anime adaption by Studio Lerche featuring Masaomi Ando as the show's director. It spanned 12 episodes from January 11, 2016, to March 28, 2016, and is licensed by Sentai Filmworks in the US.

Plot
Lux, a former prince of an empire named Arcadia that was overthrown via a rebellion five years earlier, accidentally trespasses in a female dormitory's bathing area, sees the kingdom's new princess Lisesharte naked, incurring her wrath. Lisesharte then challenges Lux to a Drag-Ride duel. Drag-Rides are ancient armored mechanical weapons that have been excavated from ruins all around the world. Lux used to be called the strongest Drag-Knight, but now he's known as the "undefeated weakest" Drag-Knight because he will absolutely not attack in battle. After his duel with Lisesharte, Lux ends up attending the female-only academy that trains royals to be Drag-Knights. (via Anime News Network)

Official
Offical Light Novel Site

Offical Manga Site

Offical Anime Site

Other Sources
Wikipedia

MyAnimeList.net (Anime)

MyAnimeList.net (Light Novel)

Anime News Network

Other Wikis
w:c:saijaku-muhai-no-bahamut - Underdeveloped alternate wiki