USJ's opening hours vary depending on the season and the day.
Some days are open from 9am to 10pm, others from 10am to 8pm, and there are many other patterns of opening hours, so be sure to check in advance before you go.
You can check the opening hours for several months in advance on the Universal Studios Japan website.
However, the scheduled opening hours may change suddenly due to weather and other factors.
It's also a good idea to check the show schedule, opening hours of attractions, and opening hours of restaurants and shops that you are interested in.
Some attractions have closing periods.
The park is so large that it's impossible to enjoy everything in a day or two, so if you want to enjoy it as much as possible, it's a good idea to do some preliminary research in advance about opening hours, schedules, and closing periods of attractions, and make a rough plan.
Also, if you have an annual Studio Pass, don't forget to check the days that are excluded from admission.
It's also a good idea to check the opening hours of parking lots, train and bus times, and the operating schedule of the sea shuttle boat, which are other things that will help you get to USJ.
You will often need to do a lot of prior research, but you can find out most things by looking at the USJ website, so be sure to check it out.
USJ opening hours