South Korean hip-hop boy band MONSTA X was formed in 2015 on the reality television competition NO.MERCY. The septet is composed of leader/vocalist/dancer Shownu (born Son Hyun-woo), vocalist/dancer Wonho (born Lee Ho-seok), vocalist Minhyuk Lee, vocalist Ki-hyun Yoo, vocalist/dancer Hyungwon Chae, rapper Jooheon (born Lee Ho-joon), and rapper I.M (born Lim Chang-kyun).
On NO.MERCY, the group performed covers of songs by Ariana Grande, Justin Timberlake, Jay Park, and others. They released their early singles -- "0 (Young)" and "Interstellar" -- during the show's run. Their debut EP, Trespass, arrived in 2015 and peaked at number five on the Korean charts. The Rush EP followed months later, pushing Monsta X to number three.
In 2016, they released a pair of mini-albums, The Clan, Pt. 1: LOST and Pt. 2: GUILTY. The EPs became their first to break into the Billboard World charts, at number five and three respectively. The third Clan installment was issued in early 2017. Titled Pt. 2.5: The Final Chapter, it topped the Billboard World chart and rose to the number two spot on the Korean chart. That year, Monsta X made their debut in the Japanese-language market with Hero.