Protocol
According to protocol, the flag may fly from sunrise until sunset; businesses and schools are permitted to fly the flag from opening to closing. When flying the flags of Japan and another country at the same time, the Japanese flag takes the position of honor and the flag of the guest country flies to its right. Both flags must be at the same height and of equal size. When more than one foreign flag is displayed, Japan's flag is arranged in the alphabetical order prescribed by the United Nations. When the flag becomes unsuitable to use, it is customarily burned in private. The Law Regarding the National Flag and Anthem does not specify on how the flag should be used, but different prefectures came up with their own regulations to use the Hinomaru and other prefectural flags.
The Hinomaru flag has at least two mourning styles. One is to display the flag at half-staff (半旗, Han-ki?), as is common in many countries. The offices of the Ministry of Foreign Affairs hoist the flag at half-staff when a funeral is performed for a foreign nation's head of state. An alternative mourning style is to cover the sphere finial by black cloth and place a black ribbon above the flag, known as a mourning flag (弔旗, Chō-ki?). This style dates back to July 30, 1912, when Emperor Meiji died and the Cabinet issued an ordinance stipulating that the national flag should be raised in mourning when the Emperor dies. The Cabinet has the authority to announce the half-staffing of the national flag.
Read more about this topic: Flag Of Japan