first appears to Karin, tries to communicate with her and eventually persuades her to leave her office and go outside. His intention seemingly is to let Karin remember the world outside and the lullaby her mother sang to her when she was an infant. After accomplishing this goal, he disappears.
It is later revealed that the boy, codenamed Canary (with no real name), was called Digma Zero, a prototype for the other Digmas (Mikuni, Kuniko and Kunihito). However, he was never allowed to step into the world outside, lived his whole life inside a facility, and died five years before the start of the series. This information also confirms that Canary lives on as a spirit of sorts. In the profile pertaining to him, his appearance is that of a blonde long-haired youth in a white jumpsuit. He keeps a black cat (which is presumably deceased as well) with a yellow bow tied around its neck as a pet.
