Hangyeom

On March 16, 2017, Hangyeom made his debut as a member of Seven O'clock with their first mini album Butterfly Effect under the name A-Day. On November 8, 2017, he was introduced as one of the participants of the reality show MIXNINE. He made it into the final group after ranking 6th and was set to debut with the male team won against the female team.

Unfortunately, on May 2, 2018, it was confirmed that the final group will not be debuting due to disagreement with YG Entertainment. On March 2, 2020, he uploaded his first song titled "Dangerous" on SoundCloud, along with a music video on YouTube. On March 2, 2021, Forest Network announced that the group had disbanded but was in discussions regarding future individual activities for the members.