Simple (reissue name A-Cha) is the fifth studio album by the South Korean boy band Super Junior.

According to Gaon Chart, as of the end of December 2012, the album has sold a cumulative total of 543,623 copies domestically.

Heechul tweeted on 2 June 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.

"[3] American dancer Kenny Wormald posted on his official Twitter on 11 July 2011, that he had started the choreography rehearsal for the group's upcoming new single.

Other photos followed, in order of: Donghae, Leeteuk, Shindong, Kyuhyun, Sungmin, Ryeowook, Yesung, Siwon and Heechul.

Songs encompassed with synthpop elements include "Opera", "Be My Girl", "Walkin'" and "My Love My Kiss My Heart".

[11] The group held a press conference at the Imperial Palace Hotel in Seoul on 4 August, which attracted over 200 reporters, including 70 foreign journalists from Japan, China, Taiwan, Thailand, Hong Kong and Singapore[12] The group expressed that they will promote the album for as long as possible till Heechul's enlistment date and also to continue with Super Show 4 World Tour.

[18] However, promotions for the song ended on 28 August due to the enlistment of member Heechul to the army on 1 September 2011.

The single album also include the travel-themed mid-tempo ballad "Way", Japanese original music video and making-of DVD.

[23] Music critic Han Dong-yoon from webzine IZM expressed boredom with the song "Mr.

Simple" due to repetition of the same lyrics and "techno-type electronic sounds"; he additionally criticized the "distorted vocals" which made identifying the members difficult, "except for a few people".