"Yūki 100%" (勇気100%,Yūki Hyaku Pāsento?, "Courage 100%") is the 21st single by Japanese boyband Hikaru Genji, released on May 13, 1993. It was used as the theme song of the animated series Nintama Rantarō, while the B-side "Hohoemi o Azukete" was used as an insert song for the same anime.
The song has been re-used four times as the Nintama Rantarō opening theme song. The original version was used for season 1 (1993–1994), while their self cover under the name Genji Super 5 was used for seasons 2 through 9 (1994–2001). Johnny's Entertainment groups then covered the song three times: Ya-Ya-Yah (seasons 10–16, 2002–2008), Hey! Say! JUMP (season 17, 2009) and NYC (season 18, 2010).
"Yūki 100%" was covered as the debut song of the Japanese boy band NYC. It was released under J Storm on April 7, 2010.
The single was released in two versions. Limited edition which includes the Promotional video and the jacket shooting while the regular edition comes out with instrumentals. The limited edition came with three NYC photo cards type A and the first press of the regular edition came with three NYC photo cards type B. "Yuuki 100%" was used as the fifth opening theme for the anime Nintama Rantaro while "Yume no Tane" its B-side was used as the 20th ending theme. It peaked at #1 on the Oricon charts and sold 120,516 copies in total in 13 weeks.