Chōhi Yokutoku, also known by her real name Rinrin, is a main character whose cheerful and talkative nature belies a deep-seated loneliness rooted in tragedy. Orphaned at a very young age when bandits killed her parents, she was taken in by her grandfather. After his subsequent death, she was left entirely alone. To cope with this isolation, she gathered the other children in her village and formed a group called the Rinrin Bandits, hiding in the mountains and pulling pranks on the townspeople. This behavior was less about malice and more a desperate cry for attention and a way to fill the void left by her family.

Her life changed forever with the arrival of the wandering warrior Kanu. The village chief, fed up with the escalating pranks, decided to have Chōhi arrested and punished. Kanu, who had lost her own family to bandits, felt a deep sense of sympathy for the girl and volunteered to bring her in herself, hoping for a kinder resolution. The two met and fought a prolonged battle that lasted late into the night. During the fight, Kanu's words reached through Chōhi's defiant exterior, questioning why she would inflict the pain of loneliness on others when she knew it so well. Chōhi broke down, confessing her loneliness and confusion. In a pivotal moment, Kanu offered to become her older sister. They made a vow of sisterhood, and Chōhi decided to leave her hometown and accompany Kanu on her journey to save people from the Yellow Turban Rebellion. This event is the cornerstone of her character, and she later recounts the night in a way that often causes humorous misunderstandings about the true nature of their bond.

Personality-wise, Chōhi is a spirited tomboy who almost always appears energetic and cheerful. Despite this bright exterior, she remains a fragile girl deeply affected by her past losses and terrified of being abandoned again. This vulnerability manifests as a powerful and possessive sister complex towards Kanu, whom she constantly seeks approval from and grows jealous of when Kanu shows affection or trust to others, particularly Ryūbi. In the second season, she vehemently opposed Ryūbi becoming Kanu's younger sister, fiercely guarding her own position as the sole little sister, though she eventually accepts Ryūbi as a second older sister. She is fiercely loyal and dedicated to protecting her friends, once defending a village alone against a horde of bandits even while suffering from a severe cold.

Chōhi is a deceptively powerful fighter. Although small in stature, her physical strength is immense, possibly even surpassing Kanu's. She wields a large, forked spear with tremendous power, specializing in wide, slashing attacks rather than precise thrusts. Her diminutive size gives her an advantage in speed and agility, often catching opponents off guard with her raw power. Her years leading the Rinrin Bandits also made her an expert at setting elaborate traps. However, her abilities have notable weaknesses. She lacks refined technique, making her predictable to a more skilled fighter. She also struggles with complex strategies, has little patience, and is nearly illiterate. A running visual gag in the anime is her facial expression matching the tiger-shaped hair clip she wears.

Her role in the story is primarily that of Kanu's loyal and devoted right hand, the first to join her cause and one of her most steadfast companions. Her deep affection for Kanu is expressed in many small ways, from sleeping in her lap to becoming jealous of anyone who vies for Kanu's attention. Despite her innocent and naive nature regarding romance and certain social situations, which is often played for comedic effect, her emotional core is grounded in a genuine need for family and belonging. Over time, she grows from a lonely child causing mischief into a reliable warrior, though she never outgrows her deep-seated need to be close to her beloved onee-chan. Her journey is one of finding a new family and a purpose to fight for, transforming her initial grief into a powerful strength.