The Only "R" in the world

Urus, a warrior whose family was slain by demons, dwells in a world ravaged by chaos and darkness. Obsessed with revenge, he learns of Kelg's pub, a gathering place for heroes reborn in this realm who seek allies in their battle against the demon king. Hoping to join forces with one of these legendary figures, Urus journeys to the pub, but to his dismay, a peculiar summoning ritual brands him as the weakest class and assigns him the enigmatic letter, "R." Thus begins his descent into the abyss of this world's true darkness. What, exactly, is the significance of the letter "R" and this ritual, and what horrors will Urus encounter in this forbidding realm?