Yuusha Party wo Tsuihou sareta Shiromadoushi, S-Rank Boukensha ni Hirowareru: Kono Shiromadoushi ga Kikakugai Sugiru

One day, Lloyd, a white mage, is banished from the hero’s party. Lloyd, who has lost his job, happens to accompany an S-rank party on a quest by chance. At that time, no one knew that the hero’s party would collapse and Lloyd would gain fame… yet. This is the story of an extraordinary support magic user who thinks he is normal and becomes an adventurer, while he is unaware of how he eventually becomes peerless.

(Source: Futabasha, translated)