United Cube Concert – One (Korean: 유나이티드 큐브 원) was the second domestic concert of South Korean music label Cube Entertainment in 2018. A total of 33 Cube artists performed, including Hyuna, Jo Kwon, BtoB, CLC, Pentagon, Triple H, Lai Kuan-lin, Yoo Seon-ho and (G)I-dle. The concert took place at KINTEX in Seoul with an audience of 8,500 people.

Two elementary boys, who are best friends and baseball fanatics, had to be separated as one left Korea to pursue education abroad. Many years later after returning to Korea for high school, the boy had found his best friend to have only turned into a girl instead.