The Cabinet of Japan consists of the Ministers of State and the Prime Minister. The members of the Cabinet are appointed by the Prime Minister, and under the Cabinet Law, the number of members of the Cabinet appointed, excluding the Prime Minister, must be fourteen or less, but may only be increased to nineteen should a special need arises.
Article 68 of the Constitution states that all members of the Cabinet must be civilians and the majority of them must be chosen from among the members of either house of the National Diet
The precise wording leaves an opportunity for the Prime Minister to appoint some non-elected Diet officials.