Haiiro no Ash ~Teikoku Kishidan wo Kubi ni Natta Ore wa Dungeon Toshi de Haiiro no Jinsei wo Hikkuri Kaesu~

Read Manga 灰色のアッシュ～帝国騎士団をクビになった俺はダンジョン都市で灰色の人生をひっくり返す～ / Haiiro no Ash ~Teikoku Kishidan o Kubi ni Natta Ore wa Dungeon Toshi de Haiiro no Jinsei o Hikkuri Kaesu~

Ash was living a life that seemed perfect in both his public and private affairs—serving as a captain in the Imperial Knights and even having an adorable noble fiancée. However, one day he is suddenly told that he is being expelled from the knight order and that his engagement is canceled!?
Fed up with everything, Ash decides to leave for a new land.
The place he heads to—the Kingdom of Rosebell—is a nation far more advanced than the Empire, which has been rapidly growing by exploiting dungeon resources. There, he reunites with his old friend Bale. In the kingdom’s second dungeon city, Ash begins a new life as a hunter. With his overwhelming strength, he steadily gains fame.
Meanwhile, back in the Imperial Knights where Ash is no longer present, his junior Ulka—who absolutely adores him—changes her demeanor and prepares to chase after him.