Unfortunately, Kasumi doing most of the things for Sumire, in addition to Sumire not being skilled enough to go into gymnast competitions uncontested like Kasumi even if they received the same training, had resulted in Sumire developing a severe sense of inferiority towards Kasumi, and suicidal depression manifesting as a constant sense of worthlessness and (heavily implied) quick fatigue. She also promised Sumire that they would go to internationals as a duo one day, although this is a promise which can no longer be fulfilled. Kasumi is said to be a literal gymnastic genius who constantly goes into local competitions virtually uncontested, and many people were stunned by her bold performances. This excludes preparing the dishes since she cannot do them properly. She also decides most of the matters between the Yoshizawa sisters, including designing Sumire's bedroom.

She and Sumire had been practicing gymnastics since childhood under Coach Hiraguchi who trained them with a spartan degree, although Kasumi had a much more natural and shorter learning curve compared to her younger sister. They also lived alongside their mother and grandmother. Kasumi is an accomplished gymnast living alongside her sister Sumire Yoshizawa and the sisters' father Shinichi Yoshizawa, who was the host of a talk show at Akasaka Mitsuke. Kasumi is also said to not support handling matters for others to prevent them from being over-reliant on other people, something she doesn't follow towards Sumire. When Sumire's frustration and mental instability reaches its peak, Kasumi's response is to joke around her, resulting in her subsequent breakdown that led to Kasumi's death. While possessing obviously well-meaning intent on taking care of Sumire, Kasumi can be highly insensitive or oblivious to her younger sister's depression plummeting to near-suicidal levels because of her care.

Sumire had even described her as a 'perfect sister.' Despite this, Kasumi does have one inferiority compared to Sumire she cannot cook as well as her. She is also much more nimble, has better memory than Sumire and can execute complex gymnast moves without any issues, something that the fake Kasumi cannot do. Kasumi is largely implied to have the same personality as the 'Kasumi' who is actually Sumire under Maruki's spell, aside that she is much more bold and confident and is fully consistent in her performances and cheerfulness, said to be consistently at top score during gymnastic competitions and would do her best to cheer up her sister or protect her from harm. She also wears contact lenses and her gymnast outfit is pink instead of blue.Д«ecause Kasumi was deceased right before the events of Persona 5 began, and thus was unable to speak for herself, most of her personality and history are only known by the accounts from Sumire's Confidant, as well as her behavior when she identifies herself as Kasumi. However, her eyes are brown and more angular compared to her younger sister and she has auburn hair and a beauty mark next to her left eye.

Kasumi is a young girl with identical facial features to Sumire.

Persona 5 kasumi