Minerva ranks as the fourth among the six Jupiter Sisters, celestial priestesses chosen by heaven who sealed Old Hell through self-sacrifice centuries ago. Residing within her human host, Shiori Shiomiya, after the seal's mysterious break, Minerva shares Shiori's inherently shy and timid personality. The divine power of these non-blood-related sisters originates from their collective bond; losing any member would shatter this bond and require new guardians.

Exhibiting profound timidity, Minerva mirrors her host's reserved nature. A constant bookworm, she observes events while engrossed in an unnamed book. Her wariness of others severely hinders communication, causing her to shrink from interaction until she deems individuals trustworthy. This timidity shapes her magical approach, favoring indirect methods like deploying force fields over direct aggression during confrontations. When manifesting control, Minerva appears as a childlike version of Shiori's younger self. Her distinct physical form features a modified uniform resembling a one-piece dress, light-blue-tinted hair elongating to her hips, wings, a halo, and ribbons, setting her apart from her fellow goddesses.

Her abilities focus entirely on support magic. She specializes in generating impenetrable force fields, demonstrated when shielding herself and Keima Katsuragi from her sisters' argument, and amplifying the powers of other Jupiter Sisters. Uniquely, she could manifest independently without reflections or shadows before obtaining her wings. Like all her sisters, her powers wane under negative emotions like rage or jealousy.

Minerva first appears during Shiori's reconquest arc. She observes Keima and Shiori from afar, teleporting away when Shiori tries to make contact, leaving her host bewildered. She silently watches Shiori's frustration with writer's block. After Shiori resolves to write a novel following Keima's encouragement, Minerva manifests directly but flees upon asking about Shiori's progress. When Shiori collapses from exhaustion after finishing her story, Minerva takes control upon Keima's arrival. Flustered by his questions, she cites Apollo's advice about avoiding strangers before relinquishing control.

Her development intensifies post-awakening. She attends a gathering summoned by Diana, initially rejoicing at their reunion. Tensions flare as sisters debate their hosts' affections for Keima; Minerva interjects that Keima "belongs to Shiori" and tries to repel Mars with her book. When Vulcan joins the conflict, Minerva envelops Keima and herself in a protective bubble. Later, she participates in reviving Apollo by amplifying her sisters' powers. During the Mai-High Festival, Vintage abducts Minerva and Shiori, leaving scattered books in the library. Following rescue facilitated by Mercury, Minerva joins her sisters in casting a spell that destroys the Vintage hideout and subsequently attends the festival, watching performances with Vulcan.

In the Heart of Jupiter arc, Minerva detects an ominous vapor enveloping the school, identifying it as a Weiss spell. She leads her sisters to its source, encounters an unconscious Keima, and assists in preparing the teleportation spell sending him ten years into the past. During Diana's arranged sleepovers, she engages in lighthearted conflicts with sisters over Keima's affections, using her magic to retaliate against Apollo and Mars for teasing her childlike appearance. She later participates in a lottery to decide who protects Keima in the past, advocating for Shiori's claim. When a Mobile Colossus attacks the library, she briefly takes control of Shiori alongside Vulcan and Mercury before escaping.

Minerva shares a close bond with Shiori, though their mutual shyness limits communication. She actively shields her host, encouraging Shiori to interact with Keima and striving to overcome her own timidity to champion Shiori's happiness. Among the Jupiter Sisters, she maintains deep respect despite frequent teasing from Apollo and Mars, reflecting their strong familial bond and shared purpose.