Nureginu de Tsuihou sareta Saikyou Kaijushi, Maboroshi no Kodai Oukoku wo Saikou sasete Musou suru: Juha no Ou to Naraku no Hime

Alf, one of the kingdom's official cursebreakers, is sentenced and punished to be thrown into the abyss for crimes he did not commit. Before his very eyes lies a never-ending labyrinth... In this dungeon, that no one has ever escaped from, Alf meets a mysterious beauty!? The curtains open to the grandiose revenge story of a man who lost everything after being betrayed by his own ally!!

(Source: Shueisha, translated)