LiEat – The Lie-Eating Dragon and the Forgotten-Color Songstress

Efina is a young dragon girl who has the unusual ability to detect and eat people's lies that have materialized into monsters. She follows Theobald Leonhart, a traveling con-man who has come to Indigo Town to check on valuable information he has received. This novel precedes the games - covering one of the first few adventures of Efi and Theo in Indigo Town. https://www.mangaupdates.com/series.html?id=135194