Shirayuki was born in Tanbarun's mountains to Mukaze and a mother who died early. Her distinctive apple-red hair drew unwanted attention, leading her grandparents to teach her concealment techniques. Raised primarily by them after her father, leader of the dangerous Lions of the Mountains, chose not to involve her, she only occasionally saw him during visits to their pub. After her grandparents' deaths, she converted their pub into a pharmacy, becoming a respected herbalist known for her expertise and rapport.

When Prince Raji Shenazard of Tanbarun ordered her to become his concubine due to her hair, she rejected him, finished pending orders, cut her long hair in defiance, and fled. During her escape, she encountered Zen Wistaria, second prince of neighboring Clarines, and his aides Mitsuhide and Kiki. Zen was poisoned by an apple Raji intended for Shirayuki, prompting her to return to Tanbarun for the antidote. Zen revealed his immunity and leveraged his status to force Raji to abandon his pursuit. Shirayuki then relocated to Clarines to build an independent life.

In Clarines, Shirayuki pursued becoming a court herbalist, passing rigorous examinations to apprentice under Chief Pharmacist Garack and prodigy Ryu. Her expertise proved vital in managing disease outbreaks and creating defensive concoctions like paralyzing agents. She moved into Wistal Castle's east wing and later accepted a two-year assignment at Lyrias's Pharmacy Institute to advance her studies. Despite her commoner status, she earned recognition and formal titles, including "Friend of the Tanbarun Royal Family" from Raji after aiding him medically despite their history.

Shirayuki maintained a strong-willed, optimistic, and compassionate personality, often prioritizing others to the point of overwork. Her independence initially made her reluctant to accept help, but she gradually learned to rely on allies like Zen, Obi, Kiki, and Mitsuhide. She formed a romantic relationship with Zen, openly committing to him despite political and social challenges from their differing statuses. Their relationship emphasized mutual support for each other's duties: Zen as prince and governor, Shirayuki as pharmacist. She explicitly stated her intent to align her career with his responsibilities to eventually reside together.

Her character evolved through challenges, including kidnappings by figures like Mihaya and Umihebi, whom she aided medically despite threats. She reconciled with Raji, encouraging his growth into a responsible ruler. Later, her work in Lyrias and reassignment to Wilant Castle positioned her near Zen after his appointment as governor of the Wirant district. Unbeknownst to her, her path to becoming a premier royal pharmacist intersected with Zen's relocation, facilitating their reunion.

Shirayuki's background included noble lineage through her father, though he was disinherited for rescuing her mother from an arranged marriage. Her eventual marriage to Zen would elevate her to princess consort of Clarines, resolving political complications. Throughout, she maintained core values of kindness, forgiveness, and dedication to herbalism, using her skills to heal others regardless of status or past actions.