Ultra Blue (stylized in all caps) is the sixth album by Japanese–American singer Hikaru Utada, released on June 14, 2006, by Eastworld.

In this album, the R&B elements that have been present since her debut are further diminished, and the majority of the songs have an electronic flavor with an emphasis on synth sounds.

[2] In the meantime, Utada held her Budokan tour Hikaru no 5,[3] and also released the hit single "Dareka no Negai ga Kanau Koro,"[4] the theme song for the movie Casshern,[5] and her first greatest hits album called Utada Hikaru Single Collection Vol.

In an interview at the time of the release of "Be My Last," she said the following;[10] In these two or three songs, there is a lot of my character and my own direct experiences, but I also feel like they are a very big world system that swirls around me.

"[17] She stated that the "old" and "falling apart" piano playing was live instrumentation, which she bought from a random clerk at a toy department store.

[13] The song "Nichiyō no Asa" is organically composed of several loops,[14] and the lyrics are based on Utada's own image of Sunday mornings as "a time for everyone to escape from society.

[18][19] Crafted as an up-tempo electro-pop number, the song "Making Love" is about Utada's friendship with her best friend who suddenly had to move to Osaka, and it is a tune that reveals her own distorted side.

[12] "Dareka no Negai ga Kanau Koro" was released before her U.S. debut, and its quiet composition, which incorporates mainly an acoustic piano and very few strings, allows the lyrics to stand more prominently.

[20] "Colors" is the oldest song on the album, and has a song-like sentimentalism throughout over a track that also includes a two-step beat,[21] with a melancholic first half that picks up quickly in the chorus.

[14][23] The ballad number "Kairo" combines strings that bring poignant and wistful imagery with an abstract rhythmic arrangement.

[10] The melancholic sound of the acoustic guitar and Utada's emotional vocals stand out in the song "Be My Last,"[14] and the elimination of the bass and use of a mixolydian mode creates a melody reminiscent of Celtic music.

"[25] "Passion" is the album's closing number and contains elements of genres such as alternative rock and ambient, with a backing track of looping tom drums and whistles.

[26][27][28] The lyrics focus on the thought, "A person in the middle of the flow of time, facing either direction in that sphere, and it is the passion and zest for life within you that connects the past, present, and future all together.

[38][37] "This Is Love" was released as the album's lead single digitally on May 31, 2006; the song was also used as a jingle for a Nissin Cup Noodle TV commercial.

[51] Daniel Robson from The Japan Times was generally positive in his review, calling it a "top-notch pop record.

[53] Ultra Blue sold 500,317 copies in its first week of release and debuted atop the Oricon Albums Chart.

[57] Ultra Blue dropped to number two on the Oricon Albums Chart on its third week of availability by selling 80,351 copies, being knocked off the top spot by B'z's Monster.