"Undefeated Weakest Bahamut") is a Japanese light novel series, written by Senri Akatsuki and illustrated by Ayumu Kasuga and Yuichi Murakami.

The empire's former prince, Lux Arcadia, accidentally trespasses in a female-only bathing area, and witnesses the new kingdom's princess Lisesharte Atismata naked and her secret.

After a duel with Lisesharte, Lux attends the female-only academy where they train students to become royal Drag-Knights.

Yuuko Kakihara handled the series composition, while Keiko Kurosawa designed the characters.

"Wyvern Knight") by True, while the ending theme is "Lime Tree" (ライムツリー) by Nano Ripe.