"Nanatsuiro Drops" is a 12-episode anime series based on a visual novel, blending elements of romance, fantasy, and slice-of-life. The story centers around Sumomo Akihime, a cheerful and somewhat clumsy middle school student who lives a relatively ordinary life. Her world changes when she encounters a magical creature named Mashiro, a tiny, rabbit-like being from the magical world of Magent. Mashiro is searching for the "Stella Cinq," a magical artifact that can grant a single wish. Sumomo accidentally becomes Mashiro's partner in this quest, binding them together through a magical contract.

As part of their partnership, Sumomo gains the ability to transform into a magical girl, using her newfound powers to help Mashiro recover the scattered fragments of the Stella Cinq. These fragments are hidden in the human world, often tied to the emotions and desires of the people around her. Throughout the series, Sumomo and Mashiro encounter various individuals whose lives are intertwined with the fragments, leading to emotional and sometimes comedic situations as they work to retrieve them.

The narrative explores themes of friendship, love, and self-discovery as Sumomo navigates her dual life as a student and a magical girl. Her relationships with classmates, particularly her childhood friend Yuuki Sanada, deepen as the story progresses. Yuuki, unaware of Sumomo's magical activities, becomes increasingly concerned for her well-being, adding a layer of tension to their interactions. Other characters, such as the mysterious transfer student Maria, play significant roles in the unfolding events, often challenging Sumomo's resolve and growth.

The series balances lighthearted moments with more poignant scenes, particularly as Sumomo grapples with the implications of her wish and the responsibilities that come with her powers. The magical world of Magent and its inhabitants, including Mashiro's rival, Nona, provide additional context and stakes to the story. The interplay between the human and magical worlds serves as a backdrop for the characters' personal journeys, culminating in a resolution that ties together the emotional and fantastical elements of the narrative.