SAMAWA, Iraq, Jan 18 (Reuters) - As Japanese troops ready for their first combat-zone deployment since World War Two, there is a buzz of anticipation in the Iraqi town of Samawa, where the 1,000-strong force will soon be based. In the central marketplace, banners have been strung across the street with welcome messages for the soldiers. "Along with our Japanese friends, we will help to rebuild this city," reads one in Arabic, while another proclaims in Japanese: "Welcome to the Self-Defence Force". An advance contingent of the Ground Self-Defence Force, as Japan's army is called, is currently in Kuwait and...