Off The Record Entertainment announced that Lee Seoyeon would not be able to participate in the promotions for My Little Society due to a leg injury on September 10, 2020.

[10] On September 11-12, they released the tracklist and the highlight medley for My Little Society respectively, revealing "Feel Good (Secret Code)" as the lead single.

[11][12] On September 15-16, they released the first and second music video teasers for "Feel Good (Secret Code)" respectively.

[13][14] On September 16, they released My Little Society along with the music video for "Feel Good (Secret Code)".

[15] They held their first live performance for "Feel Good (Secret Code)" on September 16, 2020 on Mnet's M Countdown.