CHUUNEN MAJUTSUSHI NO YUUYUUJITEKI NA DUNGEON KOURYAKU: SKILL ORB WO TSUKATTARA SAIKYOU SKILL WO TE NI IRETA NODE, SUKI NI IKIYOU TO OMOIMASU @COMIC

Dungeons suddenly appeared in the world. Humanity built a new society using items found in the dungeons and materials obtained from monsters. Haruhiko Ito, a company employee, grew tired of his busy daily life and decided to become an "explorer" to make a living by exploring dungeons. He first used several skill orbs that could grant special abilities, but they were all duds. He thought the last orb would also be a dud... but what he obtained was the strongest skill, "Magic," which allows him to acquire vast knowledge of magic! Will the former salaryman explorer become a savior with the strongest skill!? (Source: Comic Corona, translated) — Description from AniList community (anilist.co).