In a world built entirely from the essence of cuteness known as the Sun Kingdom, a small, round, and amnesiac visitor named Ganso Hoppe-chan suddenly appears with no memory of who she is or where she came from. She is a "lost child" in a magical realm populated by beings with shiny cheeks and squishy bodies. However, the Sun Kingdom is under a quiet threat. Behind its sparkling facade, a group of poisonous, toxic entities known as the Black-Cheek Team is working to transform the land into an "uncute place," a dull and unpleasant wasteland devoid of all charm. To combat this threat, a group of heroes known as the Guardians fights to protect their home, and they soon welcome the mysterious Ganso Hoppe-chan into their ranks.

Parallel to this fantasy world exists the real world, where a tired office worker named Hoho Sato is struggling. Burdened by the pressures of daily work and life, Hoho finds her self-esteem slowly crumbling, leaving her on the verge of becoming emotionally lost and directionless. She is, in her own way, a lost child of the modern era. The narrative establishes that these two separate realities are connected; somewhere at a metaphysical crossroads, the paths of the amnesiac Hoppe-chan and the despondent office worker Hoho are destined to cross, intertwining the fate of the Sun Kingdom with the emotional recovery of a human girl.

The central storyline follows Ganso Hoppe-chan as she joins the Guardian team, which includes a colorful cast of fellow Hoppe-chan variants such as Ohana (Flower), Star, Megane (Glasses), Heart, and Tiara. Together, they must uncover the secret behind the Black-Cheek Team's plot to dismantle cuteness and restore the kingdom to its former glory. As the parallel world fantasy comedy unfolds, Ganso Hoppe-chan's journey of self-discovery in the Sun Kingdom begins to mirror and intersect with Hoho's quest to find her own lost sense of purpose and self-worth in the real world. The narrative arc revolves around the mystery of Ganso Hoppe-chan's origins, the revival of the Sun Kingdom, and the subtle, magical ways the two worlds heal each other.