"Mewkledreamy" centers around Yume Yumesaki, a cheerful and imaginative middle school girl who lives with her mother and grandmother. One day, Yume discovers a mysterious stuffed animal named Mew, who comes to life and reveals that she is a dream fairy from the dream world, Mewkledreamy. Mew explains that her mission is to help humans by collecting "Dream Stones," which are crystallized fragments of dreams that can solve problems or grant wishes. Yume becomes Mew's partner, and together they embark on adventures to collect these stones.

The narrative unfolds through episodic stories, with each episode focusing on a new character or situation that requires the power of Dream Stones. Yume and Mew encounter various individuals, including classmates, friends, and even strangers, who are struggling with personal challenges or emotional conflicts. By using the Dream Stones, they help these characters overcome their difficulties, often leading to heartwarming resolutions. The series balances lighthearted, comedic moments with themes of friendship, empathy, and personal growth.

Yume is supported by a close-knit group of friends, including Kokone Fuwa, her best friend who is practical and grounded, and Shouko Komori, a shy but kind-hearted classmate. Kokone eventually becomes aware of Mew's existence and joins Yume in her adventures, adding a dynamic of teamwork and camaraderie. The series also introduces other dream fairies, such as Mew's rival, Mewtron, who occasionally complicates their missions but ultimately shares the same goal of helping humans.

As the story progresses, Yume and her friends deepen their understanding of the dream world and the significance of dreams in people's lives. The series explores the idea that dreams, whether literal or metaphorical, hold the power to inspire, heal, and connect individuals. Through their interactions with others, Yume and Mew learn valuable lessons about compassion, perseverance, and the importance of believing in oneself.

The episodic structure allows for a variety of tones and themes, ranging from whimsical and fantastical to introspective and emotional. While the overarching narrative remains light and accessible, it occasionally delves into more poignant moments, highlighting the struggles and aspirations of the characters they encounter. "Mewkledreamy" combines elements of magical girl storytelling with slice-of-life charm, creating a series that appeals to a broad audience while maintaining a focus on the transformative power of dreams and kindness.