Klara Popple, the 16-year-old eldest sibling of the Popple family, migrates with them from England to Adelaide, Australia, during the 1830s. She shoulders significant responsibility within the family, consistently acting as the "Responsible Sibling" counterbalancing her more impulsive younger sisters. Her serious demeanor, often settling into a "Perpetual Frowner," contrasts sharply with Lucy-May and Kate's energetic dispositions.

Klara embodies traditional femininity, reflected in her "True Blue Femininity" color coding. As a "Farmer's Daughter," she assists with farm labor despite the family's financial struggles. She radiates an ethereal beauty known as "The Cutie" and acts as a grounding "Cool Big Sis" presence for her younger siblings, though her reserved nature sometimes distances her from their playful activities.

Her journey includes a romantic subplot with John, a young sailor met during the family's voyage. This relationship culminates in marriage, marking a significant life transition within the series. The family history includes the loss of a sister referenced in the source material, contributing to the emotional context shaping Klara's protective instincts and occasionally somber outlook.

Klara's interactions frequently emphasize her role in maintaining family stability through hardships, a stark contrast to her sisters' carefree perspectives. Her personal journey reflects themes of duty and maturity within the immigrant family experience.