Noriko Nijō attends Lillian Girls' Academy not by choice but through familial obligation, her enrollment secured by an alumna aunt despite her indifference to the school’s Catholic traditions. Her true passion lies in Buddhist art, an interest that clashes with Lillian’s environment and isolates her from peers. This cultural clash fuels her resistance to formal customs, like addressing upperclassmen with "-sama" or using polite speech with her grande sœur, Shimako Tōdō.

Her bond with Shimako blossoms unexpectedly beneath a cherry tree, where shared moments of quiet reflection bridge their reserved natures. Though both guard their vulnerabilities, Noriko uncovers Shimako’s hidden connection to Buddhism—a secret mirroring her own devotion to sacred art. When this knowledge risks exposure, Noriko shields Shimako, claiming responsibility for a scheme that could unravel her mentor’s past, proving her loyalty and cementing her place as a petite sœur.

The rosary ceremony formalizing their bond holds little sentimental weight for Noriko, who pragmatically proposes treating the tokens as temporary symbols. Yet as Rosa Gigantea en bouton on the Yamayuri Council, she embraces her duties with calm authority, resolving conflicts through logic while confronting challenges head-on. Her growing intuition for Shimako’s unspoken emotions—a hallmark of the White Rose family—deepens their partnership, balancing her council responsibilities with safeguarding Shimako’s fragile equilibrium.

Initially detached from Lillian’s social fabric, Noriko gradually navigates its intricacies, her secular fascination with Buddhist art remaining central to her identity. Her journey weaves personal integrity into the academy’s expectations, forging a path where individuality and tradition coexist—not through compromise, but quiet, steadfast authenticity.