Obon or just Bonis a Japanese Buddhist custom to honor the spirits of one's ancestors. This Buddhist-Confucian custom has evolved into a family reunion holiday during which people return to ancestral family places and visit and clean their ancestors' graves, and when the spirits of ancestors are supposed to revisit the household altars. It has been celebrated in Japan for more than 500 years and traditionally includes a dance, known as Bon-Odori.
The festival of Obon lasts for three days; however its starting date varies within different regions of Japan. When the lunar calendar was changed to the Gregorian calendar at the beginning of the Meiji era, the localities in Japan reacted differently and this resulted in three different times of Obon. "Shichigatsu Bon" (Bon in July) is based on the solar calendar and is celebrated around 15 July in eastern Japan (Kantō region such as Tokyo, Yokohama and the Tohoku region), coinciding with Chūgen. "Hachigatsu Bon" (Bon in August) is based on the lunar calendar, is celebrated around the 15th of August and is the most commonly celebrated time. "Kyu Bon" (Old Bon) is celebrated on the 15th day of the seventh month of the lunar calendar, and so differs each year. "Kyu Bon" is celebrated in areas like the northern part of the Kantō region, Chūgoku region, Shikoku, and the Okinawa Prefecture. These three days are not listed as public holidays but it is customary that people are given leave.
Below are pictures of the Obon Festival in Sasebo Park in Sasebo, Nagasaki