W"Anata no Soba de" is Crystal Kay's 21st single, it was released on May 16, 2007. It is Kay's third and final single from the album All Yours after "Konna ni Chikaku de..." in February. This single was seen as a summer love anthem which described the feelings of a lover feeling less closer to their loved one. This track exuded a pulsing R&B beat which certifies it as a more urban sounding song. The single only featured one track and thus was released at a lower price of ¥525.
W"Eternal Memories" is Crystal Kay's debut single, released on July 1, 1999. Kay was thirteen years old when this single was released. The title track was composed by Yoko Kanno, a well-known Japanese composer and arranger. "Eternal Memories" was first heard in a commercial for "Vitamin Water" and was later recorded in full. Despite peaking at #47, "Eternal Memories" has since become Kay's eighth best selling single.
WJourney is Crystal Kay's 26th single. It was released on November 24, 2010 as the lead single to Spin the Music.
W"Kitto Eien ni" is pop singer Crystal Kay's nineteenth single. It was released on January 17, 2007 as the first single for Kay's seventh studio album All Yours. This was Kay's first single since February 2006. The song, a ballad, was used as the ending theme of the live-action film adaptation of the manga Boku wa Imōto ni Koi o Suru by Kotomi Aoki which stars Jun Matsumoto and Nana Eikura as Yori and Iku, fraternal twins who fall in love despite being siblings.
W"Koi ni Ochitara" is a song recorded by Japanese singer Crystal Kay for her sixth studio album Call Me Miss... (2006). Written by H.U.B. and Shingo.S with production handled by Sakazume MisakIt, it was released as her 17th physical single through Sony Music Japan on May 18, 2005. The single is supported with the B-side tracks "Love It Take It" and "Bet You Don't Know "; the latter track was originally included as part of her previous album Crystal Style (2005).
W"Konna ni Chikaku de..." is Crystal Kay's 20th single, released on February 28, 2007. It was Kay's second single from the album All Yours after "Kitto Eien ni". This single was used for the ending credits of Japanese anime Nodame Cantabile. In the anime, the melody from the song is used in accompaniment on the piano throughout the anime as background music. The song was then replaced after the twelfth episode of the anime by the song "Sagittarius" by Suemitsu and the Nodame Orchestra.
W"Namida no Saki ni" is Crystal Kay's 22nd single, it was released on June 11, 2008. It is Kay's first single in over a year, since the release of the single "Anata no Soba de" in May 2007. The title track was used as the commercial song for Tully's Coffee commercials throughout June. The song exhibited a new, rockier sound for the singer.
W"One" is Crystal Kay's 24th single, it was released on July 16, 2008. On March 3, 2008, it was revealed that Kay was chosen to sing the theme song to the eleventh Pokémon film Giratina and the Sky Warrior. Kay also played the voice of Nurse Joy's Chansey in the film. The film's producers had apparently been considering the singer since 2001, when she sang "Lost Child" with Shinichi Osawa and Hiroshi Fujiwara for the soundtrack of the drama Satorare. The film was released in Japan on July 19, three days after the release of the single.