Jung Kook launched his first major solo single, “Seven,” at the stroke of midnight ET Friday morning, as promised. It came with a surprise that was unpromised: the appearance of one of the hottest female rappers of our day, Latto, making a featured appearance on the track. The lyrics talk about some hot action that is due to go down between the two, but the music, however, high-energy, feels deeply chill. In other words, it feels designed to be a late entry in the “songs of the summer” derby.