Toheart/2Heart (투하트) is a duo under SM Entertainment and Woollim Entertainment. The male duo consists of Infinite‘s Woohyun and SHINee‘s Key. They officially debuted on March, 2014.
In 2014, S.M. Entertainment announced Toheart, a special unit duo consisting of Woohyun of Infinite and Key of Shinee. 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 things.
After the duo disbanded after one album, Key (4 years) later mentioned in his show 'Cheongdam Keytchen' that their friendship suffered from the whole process. In the first episode of the show (guests: Super Junior Donghae and Eunhyuk) he said:
"When Woohyun and I had the duet together, we didn't really talk about our dissatisfaction. It's better if we fight or we state our opinions. The album contained too many things that i liked. But Woohyun was like 'if you like it then i like it too', but that's not people's nature, everyone must want
something, even tho just a little. Because of that, it's a bit uncomfortable to see Woohyun. That uncomfortableness came through our friendship. It's between us two so one should take the lead to talk about it, but we both are not the type to talk about those kind of things. We really had a good relationship when we were in the unit but now, I think it's not as good as it was back then."