Josephine March, known to all as Jo, is the central protagonist of the anime adaptation of Little Women. Introduced as a spirited fifteen-year-old, she is the second eldest of the four March sisters. During the American Civil War, her family faces significant hardship after her father leaves to serve as a Union officer and their family home near Gettysburg is destroyed in the conflict, forcing them to relocate to the town of Newcord.

Jo is defined by her energetic and fiercely independent personality. She is a tomboy who chafes against the restrictive expectations of traditional femininity, often speaking her mind with a quick temper that she acknowledges as a flaw she must learn to control. Her appearance is distinctive, described as tall and thin with long limbs, gray eyes, and long brown hair she famously sells to provide her mother with travel funds to visit her wounded father. She is known for favoring practical attire, including an ink-stained scribbling suit she dons for her primary passion, which is writing.

Her deepest motivation is to succeed as a writer and find her own way in the world. This drive leads her to submit stories to local newspapers, where she initially faces sharp criticism from a reporter named Anthony. Undeterred, she perseveres, eventually earning his respect and developing a friendship that helps her grow as an author. Her literary ambitions are a core part of her identity, and a significant turning point occurs when she meets Professor Friedrich Bhaer. The professor challenges her to pursue more meaningful storytelling over sensational horror novels, a moral and intellectual influence that shapes both her career and her personal life. Their relationship deepens, and he ultimately becomes her husband.

In her role within the family narrative, Jo is the adventurous and protective sister. She shares an especially close bond with her neighbor Theodore "Laurie" Laurence, but she views him platonically and ultimately rejects his marriage proposal. Her fierce loyalty to her sisters, especially her gentle younger sister Beth, is a defining trait. After Beth falls ill and dies, Jo channels her grief and family experiences into writing an autobiographical novel, which becomes her greatest success.

The anime adaptation expands upon Jo's story with unique plotlines. During the war, she helps her family shelter a runaway slave named John, demonstrating her deep-seated compassion and defiance of injustice. Her development from an impulsive teenager into a composed woman is marked by her time in New Cord and later New York, where she works as a governess and continues to hone her craft.

In her later years, as depicted in the sequel series Little Women II: Jo's Boys, Jo has matured into the headmistress of Plumfield, a progressive school she runs with her husband, Fritz. While she is now more ladylike and composed, she retains her strong and competitive spirit. As a teacher, she is a wise and loving mentor to her students, including her own sons, nephews, nieces, and orphans like the street-smart Dan and aspiring doctor Nan. She is described as an all-loving hero and a cool teacher who understands each student in their own way, fostering their creativity through plays and intellectual adventures.

Jo's notable abilities lie in her powerful imagination, talent for writing, and natural leadership. She is resourceful and persistent, able to organize her sisters and later her students, and uses her experiences to fuel her literary work. Her journey transforms her youthful rebelliousness into pragmatic leadership, allowing her to create a community where independence and self-expression are valued.