Ryuu to Ayumu Nariagari Boukensha-dou: Youzumi to shite S-Rank Party kara Tsuihou Sareta Kaifuku Majutsushi, Suterareta Saki de Saikyou no Shinryuu wo Fukkatsu Saseteshimau

Dion, a healer, was thrown into the deepest part of a dungeon in a plot by his fellow party member. As he was facing certain death, he found a wounded dragon there. Dion healed the dragon with the last of his strength, and it turned out that it's a divine dragon named Eldora. Now that Eldora has regained her power, she will join Dion the exiled healer on a journey together as adventurers. Meanwhile, Yuki, the leader of the party that ditched Dion, was searching for him alone.......

(Source: Bunkasha, translated)