Munou to Iware Tsuzuketa Madoushi, Jitsu wa Sekai Saikyou Nanoni Yuuhei Sareteita node Jikaku Nashi

Also known as: 無能と言われ続けた魔導師、実は世界最強なのに幽閉されていたので自覚なし

by Tatematsu

Ars, the son of a an imperial aristocrat, was blessed by the gods with the gift of "hearing". However, the only effect of this gift seemed to be "better hearing," and so Ars was branded as useless and imprisoned in a tower sealed with a ward!? However, while imprisoned, Ars realized that he could hear the incantation spoken by the mages. And he could even hear the chants of the gods in the heavens with his extraordinary hearing, and this allowed him to learn legendary magic. Before he knew it, he had become the most powerful being in the world! More than ten years after his imprisonment, Ars broke the seal of his prison and entered the outside world in search of more magic he has yet to learn. However, the naive Ars was unaware of the full power of his extraordinary abilities...? (Source: Overlap, translated)