Kep1er was set to make their debut on December 14, 2021 with their first EP ''First Impact'', with pre-orders beginning on November 29.<ref>{{Cite web|date=November 29, 2021|title=Kep1er The 1st Mini Album 'FIRST IMPACT' 앨범 예약 판매 안내(211203 ver.)|url=https://cafe.daum.net/kep1er.offcl/Y1Tv/4|url-status=live|access-date=December 13, 2021|website=[[Daum]]|language=ko, ja, Chinesezh, en}}</ref> However, it was announced that the group's scheduled debut has been delayed to January 3, 2022, due to one of their staff members having tested positive for [[COVID-19]].<ref>{{Cite news|author=Choi Ji-yoon|title=케플러, 데뷔 연기…스태프 코로나 확진 여파|url=https://entertain.naver.com/read?oid=003&aid=0010871513|work=NEWSIS via Naver|date=December 5, 2021|access-date=December 5, 2021|language=ko}}</ref><ref name="2022jan3debut">{{Cite news|author=Lee Jae-hoon|title=케플러, 내년 1월3일 데뷔…'2021 MAMA' 출연 취소|url=https://entertain.naver.com/read?oid=003&aid=0010878766|work=NEWSIS via Naver|date=December 8, 2021|access-date=December 8, 2021|language=ko}}</ref> On December 14, it was revealed that group members, Mashiro and Xiaoting tested positive for [[COVID-19]].<ref>{{Cite web|date=December 14, 2021|title=Kep1er 코로나19 확진 관련 안내|trans-title=Kep1er information on COVID-19 confirmation|url=https://cafe.daum.net/_c21_/bbs_read?grpid=1ZBuS&fldid=Y1Tv&datanum=11|url-status=live|access-date=December 14, 2021|website=Daum|language=ko}}</ref>
