After finally levelling up to Level 4, Bell finds himself receiving Hestia Familia's first mandatory assignment from the Guild . and it's going to be brutal! Even after careful advanced planning, his expedition to the lower levels quickly encounters disaster after disaster, separating the party. While his allies and the partnered members of the Miach and Takemikazuchi Familias struggle to stay alive, a lost Bell encounters a mysterious underwater maiden, while Cassandra finds all of her worst premonitions becoming reality in the fourth earth shattering season of Is It Wrong to Try to Pick Up Girls in a Dungeon?