Musou no Kaitaishi

Suddenly, there were dungeons everywhere. Individuals turned as "explorers," plunging into these dungeons to retrieve materials that were exclusive to them! In an attempt to save his boyhood friend who was suffering from an incurable illness, Sakuto Kurose also journeyed into the dungeons in pursuit of the "Elixir," a medication that could cure everything. But his fellows threw him aside as useless in combat—. Amidst the dungeons and the actual world, he battles malevolent humans and beasts. And so begins an exciting battle-action set in the unearthly!