"Konosuba: An Explosion on This Wonderful World!" serves as a prequel to the main "Konosuba" series, focusing on the backstory of Megumin, a prominent character known for her obsession with explosion magic. The story is set in the Crimson Demon Village, a secluded and eccentric community known for its inhabitants' dramatic personalities and magical prowess. Megumin, a young Crimson Demon, dreams of mastering the most powerful and destructive explosion magic, despite its impracticality due to its single-use limitation and immense mana cost.

The narrative explores Megumin's journey as she strives to prove herself as a capable mage. Her determination leads her to form a pact with the Demon King's army to acquire forbidden knowledge, a decision that puts her at odds with her peers and family. Alongside her is Yunyun, a fellow Crimson Demon and Megumin's rival, who serves as a foil to Megumin's brash and over-the-top personality. Yunyun, despite her social awkwardness, is a skilled mage who often finds herself reluctantly dragged into Megumin's schemes.

The series delves into the Crimson Demon culture, highlighting their theatrical tendencies and unique traditions, such as their penchant for dramatic speeches and elaborate costumes. Megumin's family plays a significant role, particularly her younger sister, Komekko, whose innocent demeanor contrasts with the chaos surrounding her. The story also introduces Arue, a mysterious and powerful mage who becomes a mentor figure to Megumin, further shaping her path toward mastering explosion magic.

As Megumin pursues her goal, the series balances comedic moments with heartfelt undertones, showcasing her unwavering resolve and the bonds she forms with those around her. The narrative culminates in Megumin's eventual mastery of explosion magic, solidifying her identity as a Crimson Demon and setting the stage for her future adventures in the main "Konosuba" series. The prequel provides deeper insight into Megumin's character, her motivations, and the origins of her iconic abilities, enriching the overall lore of the "Konosuba" universe.