He Saves The Girl And Then Wins Her Over by Saying You're Cute - 最弱無敗の神装機竜 - Saijaku Muhai no Bahamūto

Undefeated Bahamut Chronicle is a Japanese light novel series, written by Senri Akatsuki and illustrated by Ayumu Kasuga. SB Creative has published twelve volumes since August 12, 2013 under their GA Bunko imprint.