Although he released Seo Tai Ji in 1998, he remained hidden and stayed in the United States.

[1] Awaiting his return, over a thousand fans waited at Kimpo International Airport in August 2000, with 900 policemen dispatched to control the chaos.

[2] Seo held his "comeback" concert on September 9, 2000, at the Fencing Stadium within the Olympic Park to 6,000 fans.

[3] He released the album's first single, "Ultramania", which quickly went to number one on the music charts.

[5] In 2000, the song "Ultramania" won the Mnet Asian Music Award for Best Band Performance.