Manami Kasuga is one of the younger twin sisters of Kyosuke Kasuga and the older twin by a few minutes. She is a reserved, responsible, and kind girl who serves as the homemaker of the Kasuga household, handling cooking, cleaning, and laundry in the absence of a mother figure. Despite her calm and sensible exterior, both the manga and anime reveal that she possesses a wild side that occasionally needs release. She wears glasses and usually styles her hair in a ponytail or a double bun.

As a member of the Kasuga family, Manami has esper powers, specifically teleportation and telekinesis. She is cautious about using these abilities, preferring to rely on them only when absolutely necessary, reflecting her reserved nature. Her role in the story is primarily that of a supportive family member and a grounding presence for her brother Kyosuke. She often provides practical advice and helps maintain the household stability. In the manga, she is especially fond of Madoka Ayukawa and hopes that Kyosuke and Madoka will end up together, though this preference is not depicted in the anime version. In the anime, she and her twin sister Kurumi sometimes encourage Kyosuke to make a decision between Madoka and Hikaru Hiyama. Even in the manga, Manami remains unaware of the full emotional complexity of Kyosuke’s relationship with Madoka.

Her key relationships are with her twin sister Kurumi, with whom she shares a close but contrasting bond, and with her brother Kyosuke, whom she supports without overstepping. She also interacts warmly with Madoka, showing a quiet approval of her in the manga. Manami’s development is subtle; she rarely changes her core personality but occasionally reveals hidden depths, such as her suppressed wild streak. Overall, she serves as the calm, responsible anchor of the Kasuga family and a secondary but meaningful figure in the series’ romantic dynamics.