Fuguushoku "Kanteishi" ga Jitsu wa Saikyou Datta

Ein is born with the “Appraiser” job, an ability that seems useful only for identifying things, so other adventurers treat him as dead weight. During a dungeon expedition, his own party uses him as bait to escape and abandons him to fall into the depths.

There he is saved by Yuri, a spirit of the World Tree, and her guardian Ursula. They give him a Spirit Eye, and Ursula trains him until the ability everyone mocked becomes the foundation of extraordinary strength. Returning to the surface, Ein chooses more than revenge: he will help Yuri find her sisters and become the kind of adventurer who never abandons companions the way others abandoned him.