Once, the scariest thing to Arihito Atobe was his workaholic boss, Kyouka Igarashi. Now, this ex-corporate slave faces a world where monster-filled labyrinths are the norm and teamwork is key to survival. While others are eager to charge headlong into battle, Arihito chooses to become a "rearguard": a class dedicated to helping allies from the back lines. The rearguard gig should be his ticket to avoid repeating his old life, but this opportunity may just shed new light on what it means to support one's partners and work together!