Tetsuya (born October 3, 1969, in Osaka, Japan) is a Japanese musician, best known as the leader and bassist of the rock band L'Arc-en-Ciel. Formerly known by the stage name tetsu, on December 1, 2009 he started to use his birth name. While in L'Arc-en-Ciel his name is stylized as tetsuya, whereas in his solo work it is stylized as TETSUYA.

He also does backup vocals in L'Arc-en-Ciel and has composed many of the band's songs, including "Link", "Ready Steady Go", "Finale", "Driver's High", "Stay Away", "Pieces" and "Good Luck My Way". In 2001 he started a solo career under the name TETSU69 (1969 is his birth year). On November 26, 2006, he released one song under his old stage name, and as of December 10, 2009 he uses his birth name. From 2005 to 2006 he was a support member of, Dead End front man, Morrie's solo project Creature Creature. In 2007, he married 22-year-old actress Ayana Sakai.