"Demashita! PowerPuff Girls Z" reimagines the original "Powerpuff Girls" series within a Japanese manga and anime context, blending elements of magical girl and superhero genres. The story centers around three teenage girls—Momoko Akatsutsumi, Miyako Goutokuji, and Kaoru Matsubara—who are transformed into superheroes after a mishap involving a chemical substance called Chemical Z. This substance, created by Professor Utonium and his son Ken, is intended to purify Tokyo but instead splits into three beams of light, granting the girls superpowers and altering their personalities.

Momoko, the cheerful and impulsive leader, becomes Hyper Blossom, wielding a hammer and ice-based abilities. Miyako, the studious and reserved member, transforms into Rolling Bubbles, equipped with a yo-yo and water-based powers. Kaoru, the tomboyish and athletic one, turns into Powered Buttercup, using a boomerang and lightning-based attacks. Together, they form the PowerPuff Girls Z, tasked with protecting Tokyo from monsters known as "Monsters of the Week," which are created by Chemical X, a byproduct of Chemical Z. These monsters often embody negative human emotions or societal issues, providing a thematic layer to their battles.

The series introduces a range of antagonists, including Mojo Jojo, a mischievous monkey who serves as a recurring foe, and Him, a flamboyant and enigmatic villain with ambiguous motives. The girls also face challenges from other characters, such as the Rowdyruff Boys, male counterparts who mirror their powers but lack their teamwork and moral compass. Throughout the narrative, the girls balance their superhero duties with their everyday lives, navigating school, friendships, and personal growth.

The plot unfolds episodically, with each chapter or episode featuring a new monster or threat, while also developing the characters' relationships and backstories. The manga incorporates humor, action, and light-hearted moments, staying true to the spirit of the original series while adapting it to a Japanese cultural setting. The blend of magical girl tropes, such as transformation sequences and teamwork, with superhero elements creates a unique take on the PowerPuff Girls concept, appealing to fans of both genres.