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|Full Name||Hirakawa Koharu|
|Family||Hirakawa Chiaki (Younger Sister)|
|School||First High School|
|Year/Course||Year 3 Class C Course 1 - AD 2095|
|Novel||Volume 4, Chapter 11|
|Anime||Episode 19, Yokohama Disturbance I|
Hirakawa Koharu (平川 小春) is a Course 1 student from First High School and the older sister of Hirakawa Chiaki. She was one of the representative engineers of First High School during the Nine Schools Competition.
Due to Kobayakawa's fall in Mirage Bat (Koharu was the technician responsible for Kobayakawa for the event), she lost her will to continue participating in and withdrew from the Thesis Competition. This, in turn, caused her little sister, Chiaki to feel contempt towards Tatsuya. Later, the elder Hirakawa sister, in an attempt to help her younger sister, revealed personal information to Tatsuya about Chiaki and her connection to the criminal organization taking advantage of her.