U-ka saegusa IN db (三枝夕夏 IN db, db being spelled decibel, さえぐさ ゆうか イン デシベル) was a Japanese rock band comprised of U-ka saegusa (vocals), Yuichiro Iwai (guitar), Taku Oyabu (bass), and Keisuke Kurumatani (drums). They were signed under the GIZA studio label.
They debuted in June 2002 with their first single "Whenever I think of you". 2003 saw the release of their 6th single "君と約束した優しいあの場所まで", which became a smash hit and their first first Top 10 single in the Japanese charts, peaking at nº6 in the Oricon weekly charts. With several of their songs used as theme songs for TV anime series -the most succesful ones from Detective Conan (Case Closed)-, in 2006 they were invited to participate in the massive live concert Animelo Summer Live, which reunites the most prolific singers and bands related to anime. On June 6, 2007 they released the 2-disc best album 三枝夕夏 IN d-best 〜Smile&Tears〜 to commemorate their 5th anniversary. The album was a Top 5 hit in the Japanese charts.
In October 2009 the band announced that they would be disbanding after a final tour in January 2010. The three concerts they held in Tokyo, Nagoya and Osaka got sold out. Saegusa stated that she would be retiring completely from music, though the other members will continue working with other artists.