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) Note: Chapters 11-30 were split into two parts during the original serialization.