Koi KazeKoi Kaze.

Koi Kaze (Japanese: 恋風; lit. 'Love Wind') is a Japanese manga series written and illustrated by Motoi Yoshida. It was published in Kodansha's seinen manga magazine Evening from August 2001 to October 2004, with its chapters collected in five tankōbon volumes by Kodansha. The series tells of the incestuous relationship that develops between 28-year-old Koshiro, and his 15-year-old sister, Nanoka.