Dai Nagao(長尾 大,Nagao Dai?, born 28 March 1971 in Chiba, Japan) is a Japanesecomposer, musician and producer. He was a member and composer of the popular musical group Do As Infinity from its founding until it disbanded in September 2005, although they have since reformed. He played live with the band full-time when it first started, as an acoustic guitarist until about 2001. After he would appear occasionally in a few concerts as a special guest, including their final live performance on November 25, 2005. Nagao is one of the very few Japanese artists that plays a custom double-neck acoustic guitar.
His most recent projects have included composing songs for Amasia Landscape, as well as composing for Asian bands and singers such as Seven, Sayaka Yamamoto, Mount Position, I-lulu, Voxray, Dazzfeed, Sacra, and Blazespirit. He frequently composes or co-composes songs for Ayumi Hamasaki with his most recent composition being "Return Road", released on her Party Queen album in March 2012.
In 2008 Dai began playing guitar at street venues with violinist ARIA.
Since 2011 he has been working with violinist Ayasa in a project titled Sword of the Far East. They have released 3 albums and live DVD.