Immortal Music Classics (불후의 명곡)

• Season 1 originally aired: May 6, 2008 - September 14, 2008
• Season 2 originally aired: November 30, 2008 - March 22, 2009
• MCs: Tak Jae Hoon, Shin Jung Hwan, Kim Sung Eun

Season 1

A segment of Happy Sunday, (Hangul: 불후의 명곡; Hanja: 不朽의 明曲; Bulhooae Myeonggok), is co-hosted by former Country Kko Kko partners Shin Jung Hwan and Tak Jae Hoon. Although the show initially had various co-hosts, Kim Sung Eun became the final permanent host alongside Shin and Tak. The special guest for the week is their "vocal coach", usually a famous Korean singer, although sometimes producers and composers have appeared as the special guest in past episodes. During the course of the show, the special guest's top singles (as voted by Netizens) are revealed and the "students" must sing Karaoke-style. At the end of the show, the best singer/student is chosen by the special guest and receives a special prize. This segment started from Kim Won Joon's episode where he brought in presents on his own accord. The show has typically showcased older singers from the past who may or may not be still active in the entertainment industry, including Lee Seung Chul and Kim Heung Gook. However they have also had episodes featuring more recent artists, including S.E.S., in recognition of their 10th anniversary since debut, as well as Sung Si Kyung just before he left for military service in July 2008. This show aired its final episode on September 14, 2008 and is being replaced by Kko Kko Tours Single♥Single with Shin Jung Hwan and Tak Jae Hoon as the hosts.

Season 2

Happy Sunday brought back Immortal Music Classics with the same hosts, Shin Jung Hwan, Tak Jae Hoon and Kim Sung Eun. Its first returning episode began airing November 30, 2008, replacing Kko Kko Tours Single♥Single. Kicking off the second season, Patti Kim (패티김) will be the special guest. Patti Kim was the first Korean artist to be invited and perform on Japan's NHK TV as well as Johnny Carson Show in Las Vegas, United States. In season 1, Patti Kim was one of the guests that they wanted to invite on the show but was unable to. This segment was canceled in late March 2009 and has since then been replaced with Qualifying Men.