After a heated argument with another adventurer, Kazuma is determined to prove that his companions aren't as wonderful as they seem. After agreeing to a one-day party swap, he finds himself traveling with a group of people he's never met! Meanwhile, Aqua, Megumin, and Darkness decide to show off to their new ally...with predictably disastrous results! While everyone is trying to adjust to the changes, they remain unaware of a monster that has claimed the lives of many low-level adventurers lurking in their midst...