In December 2006, TAKA was joined by YUICHIRO, the finalist of "EXILE VOCAL BATTLE AUDITION 2006 ~ASIAN DREAM~" along with KEISEI & RYO who made it until the 3rd round of the said audition, and started their activities as "COLOR".
They drew a lot of attention from the public when ATSUSHI came in as their producer and made a new start under the group name "DEEP" in 2009.

On May 31, 2011, they successfully held their first Nippon Budokan live show and gained recognition as one of Japan's top artists.
On the same year, they also released the single "Kimijanai Darekanante ~Tejina~"which made it to their all-time best in the ORICON Weekly Chart at No. 3.

The melancholy albeit positive ballade "Callin You" was released in January　2012. This is one of their 5 singles to make it to the ORICON Weekly Chart's TOP 10 in succession. In February, the group released the album "YOUR STORY". In support of this album they held a hall tour "DEEP LIVE TOUR 2012 'YOUR STORY'" which attracted about 20 thousand viewers.
In August, they released the song "GO" which became the theme song of TBS's program festival "Natsu Sacas 2012 ~Egao no Tobira~".
In September, they performed the national anthem on the game "Japan National Team vs. UAE National Team" of "Kirin Challenge Cup 2012". In December, they released a wonderful winter ballad "Yokaze" which entered the TOP10 of ORICON Weekly Chart.

In 2013, they started their live house tour around Japan under the name "DEEP BEST LIVE YEAR 2013".
In February of the same year, the much-anticipated best album "DEEP BEST" was released and ranked 3rd at the ORICON Weekly Chart.
Following the success of this album, they went on a hall tour all over Japan and ended 2013 with their FINAL live show at Shibuya Public Hall in December.

And in the following years from 2014 to 2015, they've been active on nationwide tours and released singles and albums until they announced the news about their transfer from avex to Sony Music in December 2015.
They released the singles "MAY DAY", "SING" & "Celebrate" as well as a full album "THE SINGER". The song "WISH" released on December 26, 2018 peaked at number 6 on ORICON Weekly Chart.

RYO graduated from DEEP on December 31, 2018.