D-Day is the debut extended play by South Korean singer Kim Dong-han. It was released on June 19, 2018, by Oui Entertainment and distributed by Kakao M. After Kim's stint on the second season of Mnet's survival reality series Produce 101 in 2017, he promoted as a member of JBJ with fellow former contestants for seven months. Upon the group's dissolution, he began recording music for his debut solo album. A dance record, D-Day sees Kim explore various genres on the tracks.