Also known as: 僕は存在していなかった
Boku wa Sonzai Shiteinakatta is the debut single by 22/7, as well as the Costume associated with it.
The costume consists of a light blue (which may also appear grey) short-sleeved Dress with White Collar, a light Blue Belt, a Blue Bowtie, black Kneehighs (or Black Pantyhose), and black Loafers. An Emblem of 22/7 is sewn onto the left shoulder of dress.