tripleS Aria have dropped their highlight medley for 'Structure of Sadness'.

The teaser video gives a preview of title song "Door" and "Farewell My First". tripleS Aria is tripleS' sixth subunit and first ever ballad subunit with members Dahyun, Nien, Chaeyeon, Jiwoo, and Kaede, and 'Structure of Sadness' is their debut single album set to drop on January 15 KST.

Check out tripleS Aria's highlight medley above, and let us know what you think in the comments below.