He released the album "Ultramania" which consisted of nu metal and Hardcore punk. His solo act had an effect on many South Korean boy bands such as H.O.T. and caused them to decline in popularity. His songs "Internet War" and "Ultramania" were the biggest hits of the year. After the first ETPFEST in 2001, which he founded during his comeback, Taiji was presented with hide of X Japan's Fernandes MG-360S guitar, which is yellow with pink hearts, by hide's parents and his brother, Hiroshi, to celebrate the success of ETPFEST and the first hide showcase tribute ever at a Korean rock festival.