2009: Indie band in Japan, Now or Never, and Voice
In mid-June 2009, CN Blue began to perform on the streets and in live clubs in Japan. They formally debuted as an indie band on August 19, 2009 with Now or Never. The mini-album was recorded completely in English, and failed to chart on the Oricon.
In late September, their original bassist Kwon Kwang Jin left the band and was replaced by Lee Jung Shin later that year.
Their second extended play Voice was released in November.
2010: Korean debut, ThankU, and other activities
In January, FNC Music unveiled new teaser pictures for CN Blue's debut in South Korea. Bluetory was released on January 14, 2010, and stayed at the top of the Gaon Chart for two weeks. "I'm a Loner" (Korean: 외톨이야) was promoted as the title track. The group had their first televised live stage on KBS Music Bank on January 15.
They won their first Inkigayo mutizen on January 31, 2010. The group debuted their new reality show "CN Bluetory" on the Korean music channel Mnet on February 10.
In March, the band started preparations for their first full-length album ThankU. It was released on March 20, 2010 with only one new track.
In April, their official fan club name was announced as BOICE, a combination of "blue" and "voice."
CN Blue headed back to Korea in May and released their next promotional single, "Love Light" (Korean: 사랑 빛), on May 10, 2010.
On May 19, their second extended play Bluelove was released. CN Blue held their comeback stage on M! Countdown the following day. It was promoted with the track "Love," which charted at No. 2.
After their success in Korea, the band headed back to Japan. They released their first single "The Way" on June 23. For the first time, they charted in the Oricon top 40 at No. 26.
The release was followed by "I Don't Know Why" on September 16. The song reached No. 8 on the Oricon Daily Chart. On the weekly chart, they peaked at No. 15. On the Japanese indie top chart, the band reached number one. The band embarked on a small tour across Japan in order to promote the single.
CN Blue members Kang Min Hyuk and Lee Jong Hyun starred in the Korean movie "Acoustic."
2011: Re-maintenance, First Step, 392, and In My Head
On January 9, CN Blue released their third Japanese single, Re-maintenance. They started off their 2011 Japanese promotions with a Zepp Tour in 4 cities: Osaka, Fukuoka, Nagoya and Tokyo from January 9–16.
FNC Music, their entertainment agency in South Korea, released teasers for a CN Blue comeback in February 2011. CN Blue released their first full-length album 'First Step' with the title track "Intuition" on March 21.
CN Blue made a comeback in Japan with the release of their second and last indie album "392" on September 1, 2011.They also announced that they would make their major debut in Japan on October 19, 2011 under the Warner Music Japan label. CN Blue's last indie album "392" placed 6th on the Oricon Weekly Album Chart.
CN Blue released their major debut single "In My Head" on October 19, 2011 and peaked at 3rd on the Oricon Daily Chart and 4th on the Oricon Weekly Chart with 70,000+ units sold in its first week.
2012: Where You Are," Overseas Activities
The group released a new single in Japan on February 1st, titled "Where You Are". The single reached number 1 in both Oricon's Daily and Weekly chart, making the first #1 of the group in the country.
They've successfully completed Japan Fanclub Tour 2012-which they started on 13 February-on 23 February. They had nine performances in total.
On 25 February they've become the first Korean band to perform on MTV Unplugged Japan.
After performing in Thailand and Taiwan,they returned to Korea on 29 February.
Besides, CNBLUE and FTIsland will perform on Nokia Theater in Los Angeles,USA, on 9 March !