RYTHEM (リズム) was a Japanese pop duet who were under the Sony Music Entertainment label. The talented duo was formed by Niitsui Yui a.k.a Yui (新津由衣), on piano & vocal position and Katou Yukari a.k.a Yuka (加藤有加利), on acoustic guitar & vocal position. Their debut single was Harmonia (ハルモニア), released on May 2003, which song was used as the 2nd ending theme of Naruto, a popular anime in Japan. On October 2010, the duo announced on the streaming site ustream that they would disband in 2011. After their final live at Zepp TOKYO on February 27, 2011, the duo broke up.