Bell Cranel, Hestia Familia's youngest adventurer, is stranded deep in Orario's dungeon, far below the safe floors, wounded and cut off from his allies. His sole companion is Ryuu Lion, a former A-rank adventurer now working as a waitress at the Hostess of Fertility, who fights to protect him on the dungeon's 37th floor. The Juggernaut, a catastrophic irregular monster that a villain named Jura has turned against them, blocks any route of escape while the rest of Hestia Familia races down from above.