Why does japan attack foreign counties in ww2?

From 1941 onwards: The Japanese attacked Western colonies in the Far East, conquering the countries and subjugating the natives to a treatment far worse and more barbaric than the colonial power ever inflicted. While they targeted the colonies of countries already themselves conquered by Germany, so as to assure themselves of easy victories, they also attacked British colonies knowing full well the cream of British manpower was engaged in the German war, and her far east colonies only had a skeleton garrison of second or third line troops. Countries attacked in this way:-

Holland (Dutch East Indies)
France (French Indochina, Cambodia, Laos, Vietnam)
Great Britain (Hong Kong, Malaya, Singapore, Burma, our Pacific Island colonies such as the British Solomon Islands, Borneo)
the United States (the Philipines, Wake Island)
Australia (Australian protectorates such as New Britain and neighbouring countries such as Borneo)

The battle-plan was to sweep into India, driving out the British, (with a not unfounded possibility of meeting the Germans coming the other way out of north Africa into the middle east). To press attacks on the United States by capturing Hawaii and threatening the USA's western seaboard. To drive south into an Australia and New Zealand weakened by most of their fighting armies being under British command half a world away in the German war. (Ultimately, Australia and NZ were to have been dispossessed of whites and settled as an extension of Japan by Japanese)