"Miracle! Mimika" centers on Mimika, a young girl who discovers a magical transformation device that allows her to become a superheroine. The device, known as the Miracle Bracelet, is bestowed upon her by a mysterious entity from another dimension. This world is under threat from dark forces seeking to spread chaos and despair. Mimika, initially an ordinary schoolgirl, is chosen to combat these malevolent entities, known as the Shadow Beasts, which invade her world to drain the happiness and hope of its inhabitants.

The narrative unfolds as Mimika balances her daily life with her newfound responsibilities as a protector. Her transformation into the superheroine Miracle Mimika grants her enhanced abilities, including super strength, agility, and the power to summon energy-based attacks. Alongside her is a small, sentient companion named Pipo, who serves as her guide and provides crucial information about the Shadow Beasts and their weaknesses. Pipo also assists in locating the sources of negative energy that attract the creatures.

As the series progresses, Mimika faces increasingly powerful adversaries, each representing different forms of negativity such as fear, jealousy, and hatred. These encounters challenge her resolve and force her to confront her own insecurities and fears. The story emphasizes themes of courage, friendship, and the importance of maintaining hope in the face of adversity. Mimika’s relationships with her classmates and family play a significant role, as their support often becomes a source of strength for her during critical moments.

The plot is structured around episodic battles with the Shadow Beasts, interspersed with character-driven arcs that delve into the personal struggles of Mimika and those around her. Over time, Mimika’s growth as a hero becomes evident, as she learns to harness her powers more effectively and inspire others to stand against despair. The series culminates in a climactic confrontation with the leader of the Shadow Beasts, who seeks to plunge the world into eternal darkness. Through teamwork, determination, and the unwavering belief in the power of hope, Mimika ultimately triumphs, restoring peace to both her world and the dimension from which the Miracle Bracelet originated.