Ultimate Girl: Ouka Harukaze Kyodai Otome! (Light Novel)

is the first volume of the light novel adaptayion of the anime series: Ultimate Girl. It is written by Yasuhiro Kawasaki and Illustrated by Ryusuke Hamamoto. It was released under the Dengeki Bunko Imprint in October 2004.

Synopsis
In 2003, every Monday in the big city of Tokyo, a battle between a giant monster and a mysterious giant hero UFO Man was fought. On a certain Monday in October, Koharuno Shirokin, who belongs to the track and field club of the private Futagoyama Gakuen High School, encounters a robot monster on the way to the ward tournament. A boy destined to be a savior appears in the place where he is in danger of life ...!? A slightly H and cute squadron story that became a TV animation. It's a love action comedy about love, laughter, and a maiden's innocence. In addition to the familiar white silk, buds, and Vivian from the anime, there will also be a beautiful girl with a unique ori-chara. Now, read it quickly ~.

(source: Amazon JP - Translated)