Laura Haruna, known alternatively as Hiroko Haruna or Roko-chan, is a spirited ten-year-old girl central to Hamtaro's world. She resides with her parents Forrest and Marian Haruna, alongside the family dog Brandy. After relocating to a new city, Laura's initial shyness around peers dissolved upon befriending Kana Iwata, bonding over their mutual love for hamsters. This friendship became her gateway to forming connections with numerous classmates and neighbors.

Laura shares an exceptionally close bond with her pet hamster Hamtaro, marked by deep mutual affection and daily adventures. Her fun-loving nature shines through her devotion to Hamtaro's care, though she occasionally displays impulsiveness—pouting dramatically or even running away when thwarted, as when her parents refused a CD player. Academically, she enjoys school but consistently struggles, earning poor grades and failing assignments.

She harbors a crush on popular classmate Travis Kimura, whose attention is fiercely contested by other girls. Evenings often find Laura writing in her diary while Hamtaro nibbles a treat.

In "Tottoko Hamutarō: Ham Ham Ham - Jya! Maboroshi no Princess," Laura sparks the plot by announcing a family trip to her father's hometown, prompting Hamtaro to share the news with fellow hamsters. Simultaneously, Hamtaro's recurring dreams of a distressed princess hamster intertwine with Laura's trip announcement, catalyzing his dream-driven quest.

Laura sports hazel-brown hair in twin ponytails, fair skin, a pink-and-red jacket, blue shorts, and hazy brown shoes.