In July 2004, TVXQ participated in their first SM Town project and collaborated with other label mates to release the SM Town album, 2004 Summer Vacation in
Entertainment in 2003, TVXQ began as a five-member boy band composed of members U-Know Yunho, Max Changmin, Hero Jaejoong, Micky Yoochun, and Xiah Junsu.
Micky Yoochun, who started his training only a few months before the group's official debut in December 2003, was the last member to make the cut.
The boys received phone calls from Lee and were told to attend a photo shoot session, which turned out to be a briefing for their upcoming debut. During their early recording sessions, the group was offered some tentative names to use: SM5, Dream Team, O Jang Yuk Bu (Hangul: 오장육부; Hanja: 五臟六腑; literally "The Five Visceras and the Six Entrails"), Jeon Meok Go (short for Jeonseoleul Meokgo Saneun Gorae; Hangul: 전설을 먹고 사는 고래; literally "A Whale That Eats Legends"), and Dong Bang Bul Pae (Hangul: 동방불패; Hanja: 東方不敗), the Korean name for the Chinese wuxia character, Invincible East.
It debuted at number one on the Korean charts and was the fourth best-selling record of 2005.
The album's lead single "Rising Sun" was a popular hit, and it eventually became the group's signature piece.
Inspired by the success of Bo A's Japanese music career, TVXQ signed with Japan's Avex Group in late 2004.