Haruka Hayasugi is a character who appears in the Shinkansen Henkei Robo Shinkalion franchise. She is established as the younger sister of the protagonist, Hayato Hayasugi, and the daughter of Hokuto and Sakura Hayasugi. The family resides in an apartment in the Ōmiya area. Her surname, Hayasugi, is a thematic reference to high-speed rail, translating from Japanese to mean "too fast".

In terms of her background, Haruka's age is noted to be eight years old during the events of the first anime series. She has a visual design characterized by blueish-purple hair and blue eyes.

Regarding her personality and role in the story, Haruka is consistently portrayed as a sibling figure whose presence is defined by her family connections. Her characterization remains rooted in these domestic bonds, and she is not depicted as taking part in the central narrative conflicts. She does not pilot a Shinkalion robot, engage in combat sequences, or have significant interactions with characters outside her immediate family unit. Her narrative function is consequently tied to the home life of the main protagonist, providing a familial context for Hayato and his father, Hokuto. No detailed information is available regarding her personal motivations, individual ambitions, hobbies, or a character development arc spanning the course of the story. Similarly, no specific notable abilities are documented for her character, consistent with her secondary role that does not involve participation in the mecha piloting or action elements of the franchise.