Obon is a Japanese religious custom to pray for ancestors.
This ‘Obon’, as well as being a religious event to commemorate the souls of ancestors, has the air of a national holiday, with many people traveling around the country and, for those not aware of Buddhist practices, the Obon around August 15th is just a summer vacation, though most people throughout the country maintain the tradition of visting family graves.
Though it depends on the company, most close for three to five days on and around August 15th, the middle of the Bon festival, taking this Bon festival holiday as their summer holidays.