Hisabisa ni Kentoushindan wo Uketara Saikyou Status ni Natte Ita: Tsuihou Sareta Ossan Boukensha, Imasara Eiyuu wo Mezasu

Kyle, an adventurer who has been working solo for ten years after being kicked out of his party, decides to get a health check-up for the first time in a while. To his surprise, he discovers that his hidden skill — [Late Bloomer], which gradually increases his stats day by day — has awakened. Unknowingly, he’s become one of the strongest adventurers in the world! This is the exhilarating fantasy adventure of a late-blooming middle-aged adventurer who's finally coming into his own!

https://www.cmoa.jp/title/1101420917/