When lighting is dim, the eye must adapt. Although night blindness adversely affects a person's ability to see in dim light, it does not cause complete blindness. Can a person see in complete darkness? First of all, it is impossible to see anything at all in total darkness. Total darkness means the absence of light, and our eyes depend on light to see...
A human takes several hours to fully adapt to darkness and reach its optimal sensitivity to low light conditions. The same goes for Fritz.
The kid woke up in total darkness. Paranoid because of the blinding darkness and the deafening silence, Fritz pondered on his thoughts. The kid has no idea how long it had been since the fight against the Dark Magician. Unlike the first time that Fritz was forced to use the Demon King's power where he could still see and hear what was going on, he was unconscious when he let the Demon King take over his body to defeat the Dark Magician.
