Monster or Wen Shang-yi (Chinese: 溫尚翊; pinyin: Wēn Shàngyì; Pe̍h-ōe-jī: Un Siōng-e̍k; born 28 November 1976, in Hsinchu County, Taiwan), is one of the two guitarists and leader of the Taiwanese rock band, Mayday. Monster became interested in music and the guitar while studying at the Affiliated Senior High School of National Taiwan Normal University where he also met three other Mayday members Ashin, Stone and Masa. He later became vice-president of the guitar society in high school and president of the Rock and Roll society at National Taiwan University during his university days.