MAMAMOO member and solo artist Hwa Sa's anticipated solo album 'O', which features "NA" as its title song, entered iTunes charts in various countries, landing at No. 1 and No. 10 on the worldwide and the European iTunes album charts, respectively.

In addition, the artist's second mini-album topped iTunes album charts in 13 regions, including Finland, Hong Kong, Indonesia, Malaysia, Singapore, Taiwan, Thailand, and more as of this writing. The title song also topped 5 countries: Finland, Hong Kong, Jordan, Singapore, and Taiwan.

The track list for the mini album also includes tracks “Road,” “HWASA,” “EGO,” “OK NEXT,” “just want to have some fun” and the album’s namesake track “O”. From the more emotive and haunting “Road” to the lighthearted tracks like “just want to have some fun,” the album showcases Hwa Sa's unmistakable sultry vocals and range.