sounds either like an h1 or an h4 headlamp bulb.
they both use the wire to hold them in.
here is a pic of an h1
and here is an h4
the h4 should be standard in the low beam of the zenki headlight. you might have the jdm headlights which have a black painted area around the outside of the lens (not visible from the front). if thats the case then it requires the jdm spec bulb which is an h3c i believe.
h3c


if it is an h3c you can use a regular h3 that you can get at any auto parts store and just ground out the bulb housing and then use your headlight positive wire on the h3 wire. the h3 bulb is commonly found in fog lights..
hope that helped