Because of the high fat content of Kobe beef it should be cooked low and slow.

STEAKS

Whether grilling or cooking in a pan, start on high to sear both sides.  Then turn heat down to medium.  The cooking time will depend upon the thickness of the steaks and the desired done-ness.  And a meat thermometer is a great way of ensuring the perfect result.  On average, 3 minutes each side will produce medium rare and 5 minutes each side will produce well done.  

As a guide the following temperatures should give you the done-ness you require:

52C - 125F - rare
57C - 135F - medium rare 
63C - 145F - medium
71C - 160F - well done

ROASTS

Heat oven to 40C/100F/gas mark 1/4.  Place meat in a pan and add 1 - 2 inches of water.  Put in oven uncovered.  Cooking time will depend upon size of the joint and required done-ness but on average it will take 2 -3 hours for a 2 - 3 kg joint.  The end result will be a crunchy, crispy exterior and a juicy interior.  Allow to sit for 15-20 minutes, carve and enjoy.

Thermometer temperatures and corresponding done-ness are the same as for the steaks.