Haruka used to be part of the nationally-acclaimed idol group ASRUN, and had the highest popularity ranking among all the members of the group. After a falling out with one of the members of her group, she retires from being an idol and returns to the general course at Miyamasuzaka. After her retirement, she meets Minori on the rooftop when looking for a place to read. Soon, Minori, Airi, and Shizuku invite her to create MORE MORE JUMP! with them. She initially refuses, until she is given hope by former ASRUN member Mai. 

Haruka is very charismatic, being the most popular member of the former idol group, ASRUN. In Minori's words, she is "The kind of idol who is able to give everyone hope for a better tomorrow". Haruka is a strict and dedicated person, working in regular routines of rigorous workouts to stay at an idol's standard. She restricts herself to sweets and pastries, which, in response, causes cravings. She is attentive to the schedules and specials of pastry shops. Haruka is cheeky and bold, unafraid to talk back and tease her friends. She is rather sporty, liking basketball, and as a child she was competitive, having competitions over who could eat faster. She also loves penguins, owns a ton of penguin merch, and sometimes gets emotional when receiving penguin merch as a gift.

Haruka's introduction: https://www.youtube.com/watch?v=mtg8Vgy0A7Q