The alliance you are referring to is the Axis Powers. The Axis Powers were a military alliance formed during World War II, primarily consisting of Nazi Germany, Imperial Japan, and Fascist Italy. In addition to these three major powers, several other countries joined the Axis alliance at different points during the war. Here is a list of the other countries that joined the Axis Powers:
Hungary: The Kingdom of Hungary joined the Axis Powers in November 1940. Hungary aligned itself with Germany to regain territories lost after World War I.
Romania: Romania joined the Axis Powers in November 1940. Similar to Hungary, Romania sought to reclaim territories that were lost after World War I.
Bulgaria: Bulgaria joined the Axis Powers in March 1941. They aligned themselves with Germany to regain territories lost in the Treaty of Neuilly after World War I.
Finland: Finland was not a formal member of the Axis Powers but cooperated with Germany against the Soviet Union during the war.
Slovakia: Slovakia, which was a satellite state of Germany, joined the Axis Powers in November 1940.
Croatia: Croatia was a puppet state of Germany and Italy and was formed in April 1941 after the invasion of Yugoslavia.
Iraq: Iraq was briefly under the control of the Axis Powers during the Anglo-Iraqi War in 1941.
Thailand: Thailand, known as Siam at the time, signed a military alliance with Japan in December 1941, following the Japanese invasion of Thailand.
Manchukuo: Manchukuo was a puppet state established by Japan in Northeast China in 1932. It cooperated with the Axis Powers during World War II.
Mengjiang: Mengjiang was a puppet state established by Japan in Inner Mongolia in 1939. It also cooperated with the Axis Powers during the war.
It's important to note that the level of involvement and cooperation varied among these countries, with some being more closely aligned with the Axis Powers than others.