The calendar, roughly
New Year (around January 1st), Coming of Age Day in mid-January, National Foundation Day in February, the Spring Equinox in March, a run of holidays from late April into early May known collectively as Golden Week, Marine Day in July, Mountain Day in August, Respect for the Aged Day and the Autumn Equinox in September, Sports Day in October, and Culture Day and Labor Thanksgiving Day in November round out the year. Exact dates for the equinox holidays shift slightly year to year.
Golden Week: the one that matters most
The cluster of holidays from late April into early May, known as Golden Week, is Japan's single busiest domestic travel period — trains run at capacity, hotel prices spike, and popular attractions see their heaviest crowds of the year outside cherry blossom season. See the seasonal guide for how this interacts with Osaka's spring bloom.
What actually closes
Most shops, restaurants and attractions in Osaka stay open through public holidays, unlike the New Year period itself, when many smaller businesses close for several days around January 1st. Government offices and banks close on public holidays, which rarely affects a typical visitor's itinerary directly.
Planning around a holiday
If a trip happens to fall on or near Golden Week or New Year, booking accommodation and transport well ahead matters more than usual — see when to book your Osaka hotel for the specifics.