The members of the group were trained individually for three years before they debuted and launched as 1st.One. The leader of 1st.One which is Ace is a singer in the Philippines before he turned out to be part of the group. Ace had been part and the representative of the KBS Kpop World Festival in 2015. Under his real name, he released a song ""Blow the Night Away"", and it was followed by ""Ikaw Pa Rin"" and ""Giliw"" through Star Music.