Natsu no Yakusoku

 is the 15th single by Horie Yui.

CD

 * 1) Natsu no Yakusoku (夏の約束)
 * 2) Harenohi Gensoukyoku (ハレノヒ幻想曲)
 * 3) Natsu no Yakusoku (夏の約束) (off vocal ver.)
 * 4) Harenohi Gensoukyoku (ハレノヒ幻想曲) (off vocal ver.)

Limited Edition DVD

 * 1) Natsu no Yakusoku (MUSIC CLIP)