World's Strongest Rearguard: Labyrinth Country & Dungeon Seekers, Vol. 1 (light novel)

After living life as a corporate lapdog, Arihito is reborn in a fantasy world. Strangely, the class he's assigned is the very ambiguously titled Rearguard. It seems weird, but Arihito soon figures out that though it isn't flashy, he's gained the ability to do just about everything in battle, from assisting attacking and defending to healing! As he begins his new life, he quickly gathers curious companions: his old supervisor who's younger than he is, a mysterious demi-human mercenary girl, and a gorgeous high-level swordswoman. With this bevvy of interesting ladies in his party, his journey as the greatest supporter that's ever lived!