Irony was released on the Wonder Girls' first single album, The Wonder Begins, in 2007. The
single sold nearly 15,000 physical copies and 900,000 digital copies. It was later released on
the groups debut album, The Wonder Years.
Heart to Heart was released as the lead single off of 4minute's first full-length Korean album, 4minutes Left. The song peaked at #5 on the Gaon chart and sold over 1.8 million copies. Heart to Heart was also released in Japan, where it peaked at #18 and sold nearly 10,000
copies.
