The protagonist, a dedicated player of the RPG "Dragon Slayer Academy," had raised an astounding 1000 heroes to S-rank as the game’s strongest support character. But one day, a mysterious quest window appears before him, offering a hidden quest, the chance to raise a hero beyond S-Rank, an EX-Rank. The moment he accepts, he finds himself reincarnated inside the game world of Dragon Slayer Academy…

(Source: Naver, translated)