Influenced by Black Sabbath, Led Zeppelin, and King Crimson, Ningen Isu has played an influential role in Japan's heavy metal scene from the late-1980s through the 2020s. The group formed in Hirosaki, Japan, in 1987. Guitarist/vocalist Shinji Wajima, bassist/vocalist Ken-ichi Suzuki, and drummer Noriyoshi Kamidate debuted with the self-titled album Ningen Isu in 1989, then returned with Ningen Shikkaku in 1990. Ningen Shikkaku hit number 31 in Japan and was followed by 1991's Sakura no Mori no Mankai no Shita, which hit number 57. After the release of Ougon no Yoake in 1992, Kamidate left the group and was replaced by a rotating door of drummers. The band's lineup stabilized in 2004 with the addition of drummer Nobu Nakajima, who first appeared on the album San-aku Douchuu Hizakurige. Following years of declining record sales, Ningen Isu experienced a resurgence in popularity during the 2010s, beginning with the commercial success of 2011's Shigan Raisan. Shigan Raisan reached number 59 on the Oricon Albums chart and paved the way for a decade's worth of Top 40 releases, including 2013's Mandoro (number 35), 2014's Burai Houjou (number 27), 2016's Kaidan Soshite Shi to Eros (number 22), 2017's Ijigen kara no Houkou (number 18), and 2019's Shin Seinen (number 14). This success continued into the 2020s, with 2021's Kuraku hitting number 20 and 2023's Shikisoku Zekuu debuting at number 23.
