草壁 優季

Yuuki is a mysterious girl that Takaaki meets in school at night, and for some reason she is not usually seen. She carries around a notebook called the "Trash Basket Notebook".

Yuuki used to be Takaaki's classmate in elementary school, but after her parents divorced her last name was changed from Takashiro to Kusakabe, and she had to transfer to a different school./

From url=http://en.wikipedia.org/wiki/List_of_To_Heart_series_characters#To_Heart_2