Background:

Kasumi had always dreamed of becoming an idol. Upon entering Nijigasaki, Kasumi would go on to join the School Idol Club as its most passionate member. But when the club fell into disarray, Kasumi's dreams never took off, and she would soon begin to doubt herself. Her sole presence in the club room would serve as a reminder that the School Idol Club has seen better days. Nevertheless, Kasumi still believes in the club and is determined to keep the dream alive. She would continue to strive to become a school idol and hopes to once again participate in club activities, especially with a senpai she adores. Along with Karin Asaka and Setsuna Yuki, she works with Dengeki Online.

In the anime, after Setsuna Yuki disbands the School Idol Club, Kasumi declares herself president, as the sole member remaining. In Cutest Girl, Kasumi approaches Ayumu Uehara and Yu Takasaki after overhearing them talk about school idols and convinces them to join her. She remains the president continuously throughout the club's existence, occupying a genuine leadership role, even when, arguably more capable, other people join the club.

Personality:

Although slightly self-centered and mischievous, Kasumi is a kind, friendly and lively girl who loves all things cute, and her love for idols is unrivaled in strength and inspiration. Kasumi wants to be number one in any competition she's in, and often resorts to cheating or even sabotage to achieve that goal. As a consequence, she is a sore loser whenever she achieves anything other than first place. In general, Kasumi spends a lot of her time scheming or thinking up new ways to ensure her own victory; however, these plans often fail or aren't as devious as she thinks. However, even with her scheming streak, Kasumi has the capacity to be considerate and kind to her fellow idols. For example, she tries to rile up the group when Ayumu is nervous before their live and exchanges genuine Christmas gifts with the Dengeki Online group.

She hates the nickname Kasukasu (かすかす) which roughly translates to "just barely" or "not quite", and gets in a bad mood when she is referred to with it. In All Stars, it is revealed that some bullies in her past used to call her this, hence her disdain for the nickname.

Clubs and Hobbies:

Kasumi enjoys making bread and watching idol videos. Her favorite school subjects are science and home economics, but she dislikes classical literature and history. On her days off, Kasumi will typically spend 2-3 hours baking bread, 3-4 hours watching videos, and utilize one hour of jogging. She would also devote an hour after 9pm to activities that are kept "secret" to anybody but herself.

Appearance:

Kasumi is short with a slim figure and short grey-brown hair and light magenta eyes. She wears a yellow hairpin shaped like a star and a crescent moon on the left side.