2014–present: Toheart and actuación debut

Authored by sam091094

In 2014, Key formed a duo with Woohyun from Infinite. It is a collaboration between S.M. Entertainment and Woollim Entertainment.[19]According to the members, it was their idea to form a duo since they are close friends but they weren't thinking of a musical collaboration, instead of photoshoots and similar activities.[20][21] The duo was well received, winning the Popularity Award at the 29th Golden Disk Awards.[22] Jeff Benjamin from Billboard praised the duo's vocals, and also the choreography and on-screen charisma.[23] In the same year, Key was cast as the lead role for new musical "Zorro", sharing the main role with singer Wheesung and Beast's Yoseob. "Zorro" ran from August 27 till October 26 at the Chungmu Art Hall in Seoul.[24] Key also participated in the MBC variety show "We Got Married Global Edition". His virtual wife was Arisa Yagi, a Japanese model.[25]

In March 2015, Key and CNBLUE's Jung-shin were appointed as the main presenters of Mnet's M! Countdown.[26] The same year Key collaborated with AXODUS, a duo formed by Don Spike and DJ Hanmin. Key took over the vocals for the track "Hold On," and they made a special presentation on July 25, 2015 at the Ansan Valley Rock Festival.[27] In July 2015, Key was announced to be part of the musical "In the Heights",[28] which was also performed with Japanese subtitles at Kanagawa Arts Theatre in Yokohama in 2016.[29] Key made his theatrical debut as Byeong Gu in "Save the Green Planet!", based on the 2003 film of the same name.[30] Key also had his own web show entitled "Key's Know How" produced by Mnet.[31]

In September 2016, Key made his official acting debut in the tvN drama Drinking Solo which aired from September 5 to October 25. He took the role of a student who has been studying for the civil service exam for 3 years. His character has lived an easy life so far but he's currently experiencing a life with no income.[32][33] Even though this was Key's first time acting in a network, his acting was well received by the production team,[34] stating:

Key is someone who works hard. He prepared a lot beforehand... and as an actor, he comprehensively analysed his character role. He is receiving many praise and love from the staff members. Despite having no experience in dramas at the time of his audition, his acting gave off a very fresh vibe. Furthermore, his acting and his enunciation were good and so we decided to cast him.