Super Junior 5th album 'Mr. Simple'

On March 31, 2011, leader Leeteuk announced during the interview, "At the earliest, we’ll be coming out with our fifth album this summer." Leeteuk and Yesung confirmed on their radio show "Super Junior Kiss the Radio" on June 1, 2011 that they had begun recording their upcoming album that day. Heechul tweeted on June 2, 2011 saying that the group "may be going crazy with preparations for our fifth album, but when it’s finally released, you’re all going to go mad. American dancer Kenny Wormald posted on his official twitter on July 11, 2011 that he had started the choreography rehearsal for the group's upcoming new single. On the same day, Leeteuk and Eunhyuk revealed on their radio show "Super Junior Kiss the Radio" that songwriter Jinu (hitchhiker) had contributed something for the new album. Shim Jae Won, current choreographer and former member of the disbanded SM group Black Beat tweeted a picture showing cups with Super Junior's names written on them., providing possible formation for the song's choreography, as well as two pictures of the choreography practice of the group the next day showing only the lower half of their bodies. A teaser photo was released on July 20, 2011, with the first photo featuring Eunhyuk. Other photos followed, in order: Donghae, Leeteuk, Shindong, Kyuhyun, Sungmin, Ryeowook, Yesung, Siwon and Heechul.  On the same day, it was announced that the album is set for an August 3rd release. On July 22, 2011, the group began filming the music video for their new lead single. The filming for the music video wrapped up July 24, 2011, with Shim Jaewon consistently updating the group's filming activity. On July 25, Jeon Hoon of Sonic Korea Studio announced that he is mastering the new album. Two video teasers were released on August 1, 2011, in which the first teaser gained a million views on YouTube a day after its release, the second teaser passing a million views by the second day. The first teaser, by the end of the second day, had surpassed 2,500,000 views. The digital single was released on the 2nd as well as the whole digital album format through various Korean online music sites like Melon, Dosirak and Bugs, where it became an instant digital chart-topper in South Korea in just an hour of release. That day it was also made available worldwide on iTunes, where it charted at #28. The physical format of the album was released on August 3rd. The group will also have a press conference regarding the new album on August 4th at the Imperial Palace Hotel in Seoul, and the music video itself will be revealed the same day on the conference. The music video reaching more than half a million views within the first few hours of release, and comment numbers increasing by about 200 per minute. The music video passed 1.5 million views by the end of the first day, and 3 million by the end of the second, views and comments steadily growing all over the world.

The album is mostly synthpop, with the title track, "Mr. Simple", being the last installation of the "SJ Funky" genre in which the group has been consistently pursuing since "Sorry, Sorry" (2009) and "Bonamana" (2010). Songs encompassed with synthpop elements include "Opera", "Be My Girl", "Walkin'" and "My Love My Kiss My Heart". Other tracks included in the album are the country-flavored tracks "Good Friends" and "Sunflower", an electropop number "Feels Good", a cover of a 1996 song by Jinu (hitchhiker) entitled "White Christmas", ballads "Storm" and "Memories", a Donghae-Chance-written track "Y", as well as the inclusion of subgroup Super Junior-M's Korean version of their 2011 title track "Perfection", in which it serves a purpose "to give a chance to Korean fans to enjoy the music of Super Junior-M which is appearing in various stages in Asia."

The group first held a press conference at the Imperial Palace Hotel in Seoul regarding the album and declared that this will be the group's current last studio release due to planned enlistment of group leader Leeteuk, as well as member Heechul in the army sometime in 2012. The group expressed that they will promote the album as long as possible since Leeteuk will be enlisting to the army and that they are in plans of a world tour.Leeteuk added that after his discharge from the army, they will go on to release an album afterwards. Super Junior had their debut performance of "Mr. Simple" and a non-album track called "Superman" at Music Bank on August 5, 2011, followed by Music Core on the 6th and Inkigayo on the 7th.

The album debuted at the number one spot in the Hanteo Charts, selling 79,152 copies in its first week of release. Aside from this, the album also topped the Japanese Tower Records' online album orders chart.. The album's tracks, especially the title track, managed to occupy the top ten spots in various Korean online charts like Dosirak, Bugs and Melon, as well as the physical album itself topping the real-time charts in Hanteo, Hottracks and Yes24.. The album is due for release in eleven Asian countries.