Izumi Chinatsu♀

Yukyu Academy Class 1-2. She's the older, more fidgety twin. In contrast to her little sister, she's strong-willed and hates losing. An archetypal tsuntsun girl. Perhaps due to her little sister's airheadedness, she's taken up the role of a level-headed older sister. Deep down, she wants to be babied, but due to her baby sister's antics and her own disastrous true nature, her desires can never be fulfilled. She attends the same prep school as the protagonist.

[From NekoNyan]