Toheart (Korean:투하트, commonly stylized as ToHeart) is a South Korean duo formed by Woohyun from Infinite and Key from Shinee in 2014. It is a collaboration between SM Entertainment and Woollim Entertainment.
On February 20, 2014 S.M. Entertainment released a teaser announcing Toheart, a special unit duo consisting of Woohyun of Infinite and Key of Shinee. The release was followed by a second prologue teaser which was released on February 27. After the release of a music video teaser on March 4, 2014 and a track preview video a few days later, Toheart debuted with the mini album Delicious and the music video for the title track was released on March 10. On the same day, the duo held their first showcase in the Coex Artium, hosted by bandmates Minho and Sunggyu. Jeff Benjamin from Billboard praised the duo’s vocals, and also the choreography and on-screen charisma.
Both Woohyun and Key stated that it was their idea to create this unit, since both are friends and they had interest in working with each other. They didn’t expect to do a singing collaboration project, instead thinking of photoshoots and similar. On April 7, 2014 the duo followed up their promotions with “Tell Me Why” featuring Infinite Sungyeol’s little brother, Lee Daeyeol as well as actress Mun Ka Young. The song was requested most by fans and is produced by Sweetune. It tells the story about a man’s unwillingness to let a lover go.