boku wa sonzai shiteinakatta
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.