Summoned to another world with an omni-skill

The story follows Kagami, a young man who wakes up in a dark cave with no memory of how he got there. After discovering he possesses the power of an "omni-skill," he enters a void within his subconscious where he finds steel gates with the names of various classes written on them. Only the first one, an artificer, is unlocked. Armed with his new abilities, Kagami sets out to explore the land of Sinboa and unlock new powers. Along the way, he battles fierce monsters, navigates treacherous terrain, and forms alliances with other adventurers.