Nisio Isin (Japanese: 西尾 維新, Hepburn: Nishio Ishin, born 1981), stylized as NISIOISIN to emphasize the palindrome, is a pseudonymous Japanese novelist, manga author, and screenplay writer. Nisio debuted in 2002 with the novel The Beheading Cycle (the first in his Zaregoto series), which earned him the 23rd Mephisto Prize at twenty years of age. In 2005, he began his long-running Monogatari novel series, which has been published in 26 volumes as of 2020, and was later adapted as a highly-successful anime series of the same name, produced by Shaft. His Katanagatari novels, Medaka Box manga series, Jūni Taisen novel, and The Beheading Cycle have also been adapted as anime. Between 2009 to 2016, he ranked among the top 10 best-selling authors in Japan, ranking as the best-selling in 2012 and 2