Eriko Hirano, also known by her nickname Ekko, is a recurring supporting character in Kimi ni Todoke. She is a female student at Kitahoro High School and is a classmate of the protagonist, Sawako Kuronoma, throughout their high school years.

In terms of background, Eriko is first introduced at the start of the first school year. She is most frequently seen in the company of her closest friend, Tomomi Endou, and the two are often referred to together as a pair. Her nickname, Ekko, is derived from her given name, Eriko. Physically, she is depicted with short, brown hair that reaches approximately to her ears and dark-colored eyes.

Regarding personality, Eriko initially shares the common perception of her classmates, feeling intimidated by Sawako due to the protagonist's quiet demeanor and accidental resemblance to the ghost from the horror film The Ring. However, she is not unkind. As she comes to know Sawako better, she reveals herself to be a friendly and approachable individual.

Her motivations in the early part of the story are largely social, centered on navigating the new dynamics of high school and forming her own opinions about her more enigmatic classmates. She does not have a distinct personal arc but serves as a representative of the broader student body who is neither a primary antagonist nor a member of Sawako's innermost friend group.

Eriko's role in the story is most significant during the first year of high school, where she acts as part of the bridge between Sawako and the rest of their class. Initially, she and Tomomi keep their distance, but after a nudge from Shouta Kazehaya, they begin to interact with Sawako, asking her for help with their homework and assisting her with class duties like the attendance log. Their growing acceptance of Sawako is a key step in the protagonist's journey to overcome her lonely reputation. Later, Eriko and Tomomi are instrumental in revealing the source of malicious rumors about Sawako, admitting that they heard them from Kurumi. This information allows the main characters to confront the source of the bullying.

Her key relationships are primarily with her best friend, Tomomi Endou. The two are almost always seen together, and they navigate their high school social life as a unit. They also develop a significant, if less central, friendship with Sawako Kuronuma, becoming part of the wider circle of classmates who support her. They also interact with Sawako's closer friends, Ayane Yano and Chizuru Yoshida, particularly when working together to uncover the source of the rumors.

In terms of development, Eriko undergoes a subtle but clear change from being a passive observer who is afraid of Sawako to an active, friendly classmate who stands up for her. After the first year, however, her role in the plot diminishes significantly. She and Tomomi remain in the same class as Sawako through their second and third years but are largely seen only in the background at group social events such as the Christmas party and the New Year's shrine visit, indicating they remain friendly acquaintances but are no longer central to the main narrative.

There are no notable abilities of consequence to the plot associated with Eriko Hirano.