Nisennenmondai is a Japanese instrumental rock trio formed in 1999 in Tokyo, Japan. Their members include guitarist Masako Takada, bassist Yuri Zaikawa, and drummer Sayaka Himeno, who met at a club near their university. Their name is the Japanese translation of the phrase "Y2K bug". Their recordings include Sorede Souzousuru Neji (2004), Tori (2005), Rokuon (2006), and Destination Tokyo (2009). Subsequent releases include N (2013) and Live at Clouds Hill (2015). Their performances include the Roskilde Festival in Denmark and the main stage at Sonar Sound Tokyo in 2011. Their sound includes influences from post-punk and krautrock.