the single album, written by Somi, who also participated in its composition alongside 24. It was arranged by 24 and described as an alt-R&B track. Music video On June 12, the music video teaser for "Birthday" was released. The next day, the official music video was released. The festive setting was overflowing with popping colors and playful party elements, as if the music video was portraying the song's title in the most vibrant way. It showed Somi who perfectly pulled off a variety of styles, ranging from school uniforms to party looks, showing off her "born-to-be idol" charm. Commercial performance "Birthday" debuted at number 51 on the Gaon Digital Chart for the week ending June 15, 2019. The following week, it ascended to number 22 on the Gaon Digital Chart, placing at number 8 on the Component Download Chart and at number 79 on the Component Streaming Chart. The lead single of the same name "Birthday" topped major South Korean charts including Mnet, Bugs and Soribada. It also debuted at the US World Digital Song Sales chart with "Outta My Head" at number 7 and 9, respectively. Track listing Charts Weekly charts Monthly charts Release history References 2019 singles 2019 songs Songs written by Teddy Park