A bank must use the characters "銀行" (with a pronunciation of "ginkou" and literally meaning a "bank") in its trade name.
銀行は、その商号中に銀行という文字を使用しなければならない。
Read this with the articles around it
bank
「銀行」
A person that carries on banking (銀行業) under a licence from the Prime Minister (内閣総理大臣) under Article 4, paragraph (1).
Defined inArticle 2, paragraph (1)· applies throughout the law
Prime Minister
内閣総理大臣
The head of the Cabinet. Designated by the Diet from among its own members, and appointed by the Emperor on that designation (Articles 67 and 6). The Prime Minister appoints and may dismiss the other Ministers of State at will, and a majority of them must be members of the Diet (Article 68). No Minister of State can be subjected to legal action while in office without the Prime Minister's consent (Article 75).
Written by AI using Constitution, Arts. 6, 67, 68, 75 and Wikipedia: Prime Minister of Japan as a reference.