It was released on April 10, 2018 by SM Entertainment and distributed by IRIVER as the title track of their second Korean mini album Blooming Days.
[1] "Blooming Day" is described as "a light and chic dance-pop track where the members' sweet vocal colors will be showcased.
The lyrics talk about a sweet confession to a woman with heart fluttering emotions like spring".
[5] The music video was directed by VM Project Architecture and features the members in a flower-decorated world along with scenes of the group and backup dancers dancing to the song's choreography.
[7] The group began performing "Blooming Day" on South Korean music shows from April 12 on Mnet's M Countdown.