Italy invaded a handful of countries during World War 2. This included Ethiopia, along with Albania and Greece. The Italians and Mussolini, however, were heavily pressured by Hitler and the Nazis to invade its neighbors.
The only country i know they invaded was Abyssinia(ethiopia) although that was pre WW2 1935-36. I never heard of any countries that Italy itself invaded although i believe i read some where they tried and failed at invading southern France and Greece
Japan didn't invade Germany. During World War II, Japan actually joined Germany. It was part of the Axis which included Germany, Italy and Japan. After the United States declared war on Japan, Italy and Germany, as Japan's allies, declared war on the United States.
Japan invade countries in Asia and the Pacific because they wanted to get strategic parts of the area to protect the Japanese from invaders during World War II. The more countries they could control around them, the less likely that Japan itself would sustain damage and casualties.