Saikyou no Maou ni Kitaerareta Yuusha, Isekai Kikansha-tachi no Gakuen de Musou Suru

Without possessing the unique skill blessed by the goddess, a boy named Kujou Kyouya failed to save the world. He was ridiculed as a “failed hero” at the interdimensional-level academy where returned heroes who had saved many worlds gathered. However, he became the strongest and most unique hero, having trained for 30,000 years in another world...