Maki Nishikino, a crimson-haired first-year at Otonokizaka High School with piercing purple eyes and a statuesque 161 cm frame, navigates the tension between her affluent upbringing and clandestine musical ambitions. Born into a dynasty of physicians, she grapples with familial expectations to inherit their medical legacy—a pressure fueling her initial resistance to joining the school idol group µ's, despite her profound connection to music. The Nishikino family’s luxury properties, from seaside retreats to alpine lodges, inadvertently become sanctuaries for the group’s rehearsals and camaraderie.

Her tsundere demeanor masks vulnerability, manifesting in prickly defiance during group outings and fiery exchanges with fellow member Nico Yazawa, their clashing wills mirroring each other’s stubborn pride. Yet beneath her guarded exterior lies whimsical innocence, epitomized by an earnest belief in Santa Claus that defies her poised intellect.

As µ's chief composer and vocal architect, Maki’s genius shapes their sound, blending lyrical sensitivity with technical precision through piano and flute. Academic prowess—a product of rigorous discipline—earns her consistent top marks, though a rare lapse nearly costs her idol status, exposing the fragile balance between duty and passion.

Her evolution from a solitary pianist to µ's vice president traces her reluctant embrace of collaboration. Bonds with first-years Rin Hoshizora and Hanayo Koizumi soften her edges, while rivalry with Nico matures into tempered respect. Private moments stargazing or scribbling diary entries betray her inner duel: the dutiful heiress versus the artist yearning for autonomy.

Quirks like a tomato-centric diet, aversion to tangerines, and a wardrobe accented in crimson punctuate her identity. Supplementary writings, such as "Maki's Diary," unveil her self-image as a caged "princess," her ultimate rebellion crystallizing not in defiance but in the quiet triumph of choosing music—a testament to self-authorship over predestined paths.