During her third year in middle school, following the influence of her mother, YUI began keeping a journal of everyday feelings and poetry. Because of this, by the time she was in high school, she began writing songs. While in high school, she worked a part-time job to help pay for tuition. Always busy, with her time steadily disappearing, she thought there was no longer a road to music. Eventually, her body broke down and she found herself under hospitalization. While in the hospital, with the time to consider her life, she was overwhelmed with the desire to make music. She decided that school and music could not coexist. Upon leaving the hospital she encountered a live street performance and expressed her desire to pursue a musical career to the band, Bianco Nero, at the end of the concert. Bianco Nero recommended YUI that she should join a private music school. Soon, she dropped out of high school and dedicated her time studying songwriting and guitar at a juku in her hometown of Fukuoka.[1] Aspiring to become a professional, she carried her guitar around and sang at local places at the entrance of Tenjin station in Fukuoka. Doing these street performances helped YUI to eventually overcome her shyness.

In March 2003, she sang three songs at an audition hosted by Sony Music Japan, as opposed to the audition rule that a participant could only sing two songs. All judges evaluated her with the highest score, which caused a fierce scramble among labels. She first sang "Why Me", which was later coupled with her debut single, followed by "It's happy line" and "I know", the latter of which was included on her indie single. Sitting cross-legged on the floor, she strummed her guitar and sang. The judges and the others present claimed that "the performance created a tremendous aura from her heavenly voice, and captured the hearts of the whole audience".

Upon leaving her home of Fukuoka for Tokyo, YUI wrote the song "Feel my Soul". She was planning its release on an indie label as a tribute to her hometown, when the song caught the ears of Fuji TV producer Mr. Yamaguchi, who happened to see the demo video clip. He claimed YUI's voice haunted him so much that he went out of his way to visit the recording studio himself. He even made his channel's prime time drama an extraordinary tie-in with YUI's debut track.

Although she is uncomfortable talking to people, she enjoys communicating with her audience at street performances in the Tenjin district of Fukuoka.

YUI also starred in a movie released on June 17, 2006, titled Midnight Sun (in Japanese Taiyo no Uta (タイヨウのうた, song of the sun), which was screened at the 2006 Cannes Film Festival.

*It’s happy line - 2004.12.24

*feel my soul - 2005.2.23

*Tomorrow’s way - 2005.6.22

*LIFE - 2005.11.9

*TOKYO - 2006.1.18

*FROM ME TO YOU - 2006.2.22

*Good-bye days - 2006.6.14

*I remember you - 2006.9.20

*Rolling star - 2007.1.17

*CHE.R.RY - 2007.3.7

*My Generation / Understand - 2007.6.13

*LOVE & TRUTH - 2007.9.26

*Namidairo - 2008.2.27

*SUMMER SONG - 2008.7.2

*again - 2009.6.3

*It’s all too much / Never say die - 2009.10.7

*GLORIA - 2010.01.20

*to Mother - 2010.6.2

*Rain - 2010.11.24

*It’s My Life / Your Heaven - 2011.1.26

*Hello ~Paradise Kiss~ - 2011.6.1

*Green a.live - 2011.10.05

*Fight - 2012.9.5

*FROM ME TO YOU - 2006.2.22

*CAN’T BUY MY LOVE - 2007.4.4

*I LOVED YESTERDAY - 2008.4.9

*MY SHORT STORIES - 2008.11.12

*MY SHORT STORIES [Blu-spec CD] [Limited Release] - 2009.9.2

*HOLIDAYS IN THE SUN - 2010.7.14

*HOW CRAZY YOUR LOVE - 2011.11.02

*GREEN GARDEN POP - 2012.12.5

*ORANGE GARDEN POP - 2012.12.5

映画「クローズド・ノート」Music Movie with YUI - 2007.9.5

Thank you My teens - 2007.11.14

HOTEL HOLIDAYS IN THE SUN - 2011.3.9

Cruising ~HOW CRAZY YOUR LOVE~ 2012.3.28

*タイヨウのうた (Taiyo no Uta) ~ A song to the Sun - 17 June 2006