Official title of the head of the Japanese cabinet government. Often abbreviated to 総理大臣 or 首相 in everyday usage.
The Prime Minister is designated from among the members of the Diet.
The new Prime Minister has taken office.
He took office as the new Prime Minister.
He served as Prime Minister for five years.
He was appointed Prime Minister by the Emperor.
内閣総理大臣 is the full official legal title, while 総理大臣 is the everyday abbreviated form of the same position.
内閣総理大臣 is the full, formal official title, while 総理 is the shortened form used in everyday speech and news.
国務大臣 refers to an ordinary cabinet minister, whereas 内閣総理大臣 is the specific title of the Prime Minister who heads the cabinet.