Seo In Young is celebrating a very special friend's debut anniversary.

On July 1, the singer took to her personal Instagram account to share a set of images featuring her with good friend and former miss A member Fei. In the images, Fei is holding a bouquet of bright pink flowers as the pair pose warmly for the camera.

"Our Fei, happy nine-year debut anniversary," she captioned the images.

Miss A first debuted on July 1, 2010 with the single "Bad Girl Good Girl," the title track off their first album 'Bad But Good.' The group went on to release a number of hit songs, including "Breathe," "Love Alone," "Touch," and "Good Bye Baby," before their eventual disbandment on December 27, 2017.

Meanwhile, Seo In Young and Fei both currently appear on the SBS Mobidic beauty program 'Bar Persona.'

Check out the Instagram post below!