Academy's Reincarnated Hero is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

The first-generation hunter and the hero who established all monster subjugation systems and frameworks, Kim Jun-woo, finally defeats Gigantiana in the subjugation of the Black Grave Dungeon. However, he also loses his life in the process.

As his breath fades, he hears the voice of Gigantiana...