Blue Letter is the second extended play by the South Korean singer Wonho. It was released on September 14, 2021 by Highline Entertainment and distributed by Kakao Entertainment. Wonho was involved in the writing and production of all tracks in the EP, alongside contributors including Enan, Sun Ahn, Savage House Gang, and Oshimaxx. Musically, the EP consists primarily of pop songs, with elements of dance and R&B.
To promote Blue Letter, Wonho released the single "Blue" alongside the EP and held a promotional concert titled We Are Young, which took place on November 2021 in Seoul. He also made several appearances on South Korean music shows, performing the EP's lead single and select album tracks.
The EP peaked at number 5 on South Korea's Circle Album Chart and has sold over 70,000 copies in the country. Internationally, it reached number 86 on the Billboard Japan Top Download Albums chart. The lead single "Blue" charted on digital download charts in both South Korea and the United States.
In 2020, Wonho signed with Highline Entertainment following his departure from boy group Monsta X after allegations of unpaid debt and drug use were investigated and cleared. In 2020, he made his solo debut with the first part of his EP, ', which was supported with the single "Open Mind". He later released the second part of the EP, ' (2021), with support of the single "Lose".
On August 20, 2021, a teaser image announcing the release of Wonho's second EP, Blue Letter, was posted by Highline Entertainment on his social media channels. On August 28, a scheduler revealing new content prior to the album's release was unveiled. The EP's tracklist was revealed on September 7, announcing "Blue" as its title track. Prior to the release of Blue Letter, two teasers for the "Blue" music video were published on Wonho's YouTube channel. Blue Letter was ultimately released on September 14, 2021, alongside its single "Blue".
Wonho revealed that he struggled during the recording of Blue Letter, explaining that his throat was not in optimal condition and that he recorded the album in his dressing room while using multiple humidifiers. Wonho attributes "No Text No Call" as the song that helped consolidate the concept for Blue Letter, adding that it was the first track written for the EP. During the promotions of his single album Facade (2022), Wonho described Blue Letter as being dedicated to those who supported the singer during difficult periods and made to provide consolation to listeners going through similar situations, in contrast to his more recent releases.
According to Wonho, the title of Blue Letter comes from the English expression "feeling blue", commonly associated with sadness or depression. He further explained in an interview with NME that he wanted to reinterpret the meaning of the phrase to convey a sense of "feeling loved", thereby giving it a more positive connotation. He has attributed his use of the color blue in album artwork to synesthesia, explaining that he associates the color with his fans.
The release of Blue Letter was supported by its lead single, "Blue", which was released alongside the EP. A music video for "Blue" was released the same day at 6 pm KST. The physical release for Blue Letter was separated in three numbered CD versions. Throughout the promotional activities of the EP, choreography videos of album tracks were released on Wonho's YouTube channel. Special music videos filmed by Wonho for "Come Over Tonight", "24/7", "No Text No Call", and the english version of "Blue" were released throughout 2023âÂÂ2024.
Promotional activities for Blue Letter began on September 17, 2021, with a performance of "Blue" and "24/7" on KBS' Music Bank, followed by appearances on SBS' Inkigayo and MBC M's Show Champion on September 19 and 22 respectively. A performance of "Blue" took place on September 25 for MBC's Show! Music Core, which was followed by an appearance on SBS M's The Show on the 28th, performing "Blue" and "24/7". On September 29, Wonho performed the English version of "Blue" on Show Champion. A televised appearance at the 2021 Seoul International Music Fair on SBS M took place on October 1, in which Wonho performed "Open Mind" and "Blue". On October 2, a performance of "Blue" was televised on Show! Music Core, followed by an appearance on Inkigayo the next day.
A promotional run for "Come Over Tonight" was announced on October 11, beginning on M Countdown on October 14. It was followed by appearances on Music Bank and Show! Music Core on October 15 and 16 respectively. The performances featured Honey J, the leader of street dance crew HolyBang, who appeared on Mnet's Street Woman Fighter.
A promotional concert for Blue Letter, titled We Are Young, was announced by Highline Entertainment on October 13, 2021. Two shows took place between November 13 and 14 on the Yes24 Live Hall in Seoul, South Korea. It marked his first in-person concert, following a series of online concerts being held due to the COVID-19 pandemic.
Singers Soyou and Yoo Seung-woo participated in the concert as guest performers. During the November 14 show, Wonho temporarily stopped performing after experiencing hyperventilation. After receiving medical attention on site, the concert resumed.
Musically, Blue Letter is a pop EP that incorporates elements of dance and R&B. Wonho participated in writing and composing for all songs in the EP. The first track of Blue Letter, "Intro: Seasons and Patterns", is a two-minute instrumental track built around a minimal motif of two three-note phrases. Halfway through the song, a beat and strings are introduced. Nearing the end, a key change occurs, bringing a brighter tone to the track. "Blue", the EP's lead single, is a dance-pop track, with lyrics which feature a double entendre about depression and the color of the sea. The EP includes two versions of the song: a Korean version written by BrotherSu, and an English version. "No Text No Call" is a guitar-centric track about a sudden break-up. "Come Over Tonight" features 808 and synth bass, vocoder elements and a melody reminiscent of doo-wop. In the EDM track, "24/7", Wonho sings about staying beside someone "24 hours a day, 7 days a week." "Stranger" is an acoustic song, which only features an acoustic guitar, and Wonho's vocals.
In a review for PopMatters, Ana Clara Ribeiro rated Blue Letter 7 out of 10, describing the EP as a "refreshing and enjoyable work", noting that despite it exploring several genres, it does not sound "as busy as its genre classifications make it seem." Writing for NME, Rhian Daly rated the EP 4 out of 5, describing the EP as a "soul-stirring, sensitive release," noting its emotional shifts from celebratory moments to vulnerability. Writing for TV Daily, Kim Ji-ha compared the EP to Wonho's previous projects, noting its "different vibe", while Kim Han-gil and Park Sang-hoo described it as "charming" and "refreshing", respectively. Park added that the EP would have benefitted from a release in the middle of summer.
Blue Letter debuted at number five on the Circle Album Chart and remained on the chart for a total of nine non-consecutive weeks. It also appeared on the monthly chart for three consecutive months. As of November 2021, the EP had sold 78,758 copies domestically. On the Circle Retail Album Chart, the EP debuted at number six, holding its peak position for a second week and charting for seven consecutive weeks in total. It additionally debuted at number 11 on the monthly retail chart, remaining for two consecutive months. Internationally, Blue Letter charted for one week on the Billboard Japan Top Download Albums chart at number 86.
The album's title track, "Blue", debuted at number 30 on the Circle Download Chart, rising to a peak of number 22 the following week before exiting the chart. It also appeared on the monthly download chart at number 58. Additionally, the song charted for one week on the Circle BGM Chart at number 67. It also debuted at number 14 on the Billboard World Digital Song Sales chart.
Credits adapted from the EP's liner notes.