Yakusoku no Oka

 (約束の丘) is the seventh single by X21.

Single Information

 * Lyrics: Komuro Tetsuya (1), leonn (2), Mio Aoyama (3)
 * Composition: Komuro Tetsuya (1), Hibino Hirofumi (2), Kuwatani Misa (3)
 * Arrangement: Komuro Tetsuya (1), Hibino Hirofumi (2), Shimizu Takehito (3)

CD+DVD CD

 * 1) Yakusoku no Oka (約束の丘)
 * 2) 3 Dome no First love (3度目のFirst love)
 * 3) Who is X!?
 * 4) Yakusoku no Oka (約束の丘) (Instrumental)
 * 5) 3 Dome no First love (3度目のFirst love) (Instrumental)
 * 6) Who is X!? (Instrumental)

CD Only CD

 * 1) Yakusoku no Oka (約束の丘)
 * 2) 3 Dome no First love (3度目のFirst love)
 * 3) Yakusoku no Oka (約束の丘) (Instrumental)
 * 4) 3 Dome no First love (3度目のFirst love) (Instrumental)

DVD

 * 1) Yakusoku no Oka (MUSIC VIDEO)
 * 2) Yakusoku no Oka (MUSIC VIDEO Off-shot)

Featured Members

 * Izumikawa Miho
 * Matsuda Rina
 * Yoshimoto Miyu
 * Komoriya Sakura
 * Tanaka Shuri
 * Nagao Mami
 * Igashira Manami
 * Shiratori Hasumi
 * Kaminaguchi Honoka
 * Yamaki Koharu
 * Suenaga Mai
 * Ozawa Nanaka