During his vacation, Atobe Arihito, a workaholic assistant, fell asleep on the bus provided by his company. When he woke up, he realized that he had died in a bus accident and had been reincarnated in Labyrinth Country. This world was filled with creatures that needed to be fought, and everyone was expected to work and form partnerships to battle them.
Arihito's old boss, Igarashi Kyouka, was also reborn in this new world and found Arihito. She explained their task to him, expecting him to work with her. However, Arihito avoided her because of her harsh demeanor.
Kyouka, angered by Arihito's decision, vowed to make him regret it. As a result, Arihito started his journey in Labyrinth Country as a Rearguard.
