Heaven-sent Apocalypsis and the Saintess of the Labyrinth

Story:

A boy born from this world alongside the summoners from Japan… They will challenge the max-difficulty dungeon! God created a labyrinth, which people challenge with guns, swords, and magic in an RPG-like world. Summoners from many other worlds particpate in this massave battle! The locally born hunter Shun quickly rises to prominence as he plays the game!! Then, he meets the twins Yua and Yuna, who have been summoned from Japan…