In the year 2123,

the world is now merged into one city, 'Uwiron City', and controlled by the powerful government called The Red Onyx.

Kang Seulgi is one of the most elite soldiers of The Red Onyx. While on a mission, she accidentally activated a time machine that brought her all the way back to the year 2019. Aimlessly strolling around the new environment, she met the cold-faced beauty, Irene.

Irene is the leader of the famous girl group 'Black Velvet', she met Seulgi while running away from her ex-boyfriend at a party. The two of them will learn that life does not only revolves around heartbreak and career, it can also be fun even with the littlest things it gives. Will friendship and relationship bloom after knowing that they belong from different times?

While embarking on a new journey together, they will unfold secrets and face consequences that lie within them. Will Seulgi be able to go back home?