On Saturday 20 February, at the first JO1 online live of 2021 "JO1 Live Streaming Concert "STARLIGHT DELUXE"", it was announced that the 3rd single of JO1 "CHALLENGER" will be released on Wednesday 28 April.

In addition, it has been also announced that on Saturday, April 17, they will hold an online showcase event to celebrate the release of JO1 3RD SINGLE "CHALLENGER", and on Sunday, April 18, they will hold an online talk event to celebrate the release of "CHALLENGER".