I would agree - keep this very simple

Go to the hotel and ask for "takkyubin" - tell the hotel

a) the address / hotel name you want it to be delivered to
b) the date you want it delivered

Bear in mind that a long distance might require 48 hours to get to it's destination but the hotel will be able to advise you.

It will cost you circa 1,000 - 3,000 yen per piece of luggage depending on it's size and weight.

Once you've filled out the delivery form and given the hotel the right money you can forget about your luggage till your destination and it *WILL* be there.

Japanese takkyubin are VERY VERY VERY reliable so be assured it will be there on time and intact.

-mrploddy