yyxy is Loona's third subunit.

K-pop girl group Loona (stylized LOO??) has teamed up with Grimes for yyxy's first single “Love4eva.” Released on Wednesday (May 30), the saccharine electro-pop tune is the first song from the four-member unit.

The song begins with a Grimes intro that kicks off the infectious melody. “Hello,” says the Canadian artist, in what appears to be a nod to Girls’ Generation’s iconic 2009 hit “Gee.” “Finally introducing Loona. Are you girls ready? Okay. Let’s go!”

Both “Gee” and “Love4eva” were co-written by South Korean songwriting duo E-Tribe.

Following the opening, the song grows into a vibrant dance track that soars between the upbeat chorus, sweet verses, and a dubstep-style breakdown that bridges it all.

Loona is a 12-member act that had a lengthy rollout previously unheard of in the Korean music industry: since October 2016, each of the women have been introduced with solo songs and music videos, and then released music through subunit’s. Loona yyxy features Yves, Chuu, Go Won, and Olivia Hye, the final four members of the group revealed ahead of Loona’s impending formal debut as a fully-formed dozen. yyxy is the group's third subunit, following 1/3 and Odd Eye Circle.

“Love4eva” was released with a music video that features the quartet in what appears to be a finishing school, where they’re locked in and want to escape their studies to just enjoy. Clueless-esque plaid outfits abound, adding a charming throwback vibe.

The song is the lead track on Loona yyxy’s EP beauty&thebeat. Along with the single, it features four other tracks.

Grimes and Loona got in touch with one another earlier this month after the Korean act reached out to the singer-songwriter on Instagram.

"It was a huge surprise to learn that Grimes had listened to Loona's music," Loona told Billboard via email. "We were so excited! We decided to ask Grimes for a featuring verse on our new track, and when we finally got the audio files with Grimes' voices, we have never screamed longer or louder ever since the start of Loona. The collaboration of Grimes and Loona is the most unforgettable, super-exciting moment."

Watch the music video: