Hahaha, god, I just finished re-watching that show. I wish more generic fantasy animu like that was made, I enjoyed it for some god damn reason.>>11322634
My bet? The K series is the first in the Hirgana alphabet other than the A-I-U-E-O series, so I imagine it's probably just a generic name to get the concept of naming something out of the way, though IIRC "Tarou" is something like "John" so far as popularity in Japan, though I heard that a looong time ago.
tl;dr? Because no-one gives a fuck what their name is.