綾瀬 ルコ

Ruko is Yuuto's older sister. She works as a private secretary to a company president. She is skilled in karate and is a 2-dan. She is a hard worker, though she drinks a lot at home and is unable to do any housework which makes Yuuto in charge of all the chores. She generally has a rough attitude and will often speak in a brutish manner. Since her parents are absent so often, Ruko takes up the position as the highest person in the house with her brother. When first meeting Haruka, Ruko was very pleased with her, though Yuuto regarded this as unusual. She is a weapon fanatic, which is proven by the fact that she owns many magazines about weapons. She also has her personal favorite Japanese blade called Ruri Dokuro, which means lapis lazuli skull. Her battle skills are considered at the professional fighter level. This is demonstrated when she completely broke the Tennouji's household security with Yukari looking for Yuuto when he had to stay one week for his butler part time job and forgot to make food for them.

Taken from url=http://en.wikipedia.org/wiki/Nogizaka_Haruka_no_Himitsu#Characters