There are long queues for practically everything and getting reservations for the entry to the pavilions is not as straightforward as it could be, but the Expo 2025 in Osaka proved to be a very interesting experience for a fan of Japanese architecture.
The Grand Ring by Sou Fujimoto has become the centerpiece of the event as the world's largest wooden structure. It provides a shelter from the heat and rain, as well as a great viewpoint for looking at the pavilions from a higher vantage point.
Kengo Kuma designed the pavilion for Portugal, Qatar and Malaysia. As with most of Kuma's recent works, the designs are all ornamental and completely separated from the structural aspect.
Shigeru Ban designed the Blue Ocean Dome, a facility that raises awareness about plastic waste in oceans. This is the only pavilion that I managed to succeed in securing a reservation. There are displays explaining about the different material used for the three domes- bamboo, carbon fiber reinforced plastic and paper tube. Once the expo is over, the parts will be taken to the Maldives for use at a new resort that is designed by Ban.
Practical advice:
Gates open at 9am. I arrived at 8:45am on a weekday. Once the lines started moving at 9am, it took 30 minutes to clear security. The waiting area has no roof to protect visitors from the sun or rain.
Once inside, there is also not much shading other than within the Grand Ring. I can imagine it will be a huge challenge during the summer months (The Osaka heat can be much worse than Tokyo).
Closing time is 10pm. However the pavilions all close at 9pm, so you can't really do much for the final hour. There is a drone show that finishes at 9pm and that is when most visitors head towards the exit. To alleviate the crowd, you will be required to walk a very long distance in circles for the approach to the station. The trains back to the city depart frequently, but each one will be absolutely packed. Stay inside of the park a bit longer if you want to avoid the congestion. Services to the city continue until midnight, so there is plenty of time to get back into the city.
It is ok to bring your own water bottle. There are free water refilling stations inside. Also numerous vending machines selling drinks for around 190 JPY (20-30 Yen higher than the city). There are a few convenience stores inside such as Seven-Eleven or Lawson. The prices looked the exact same as outside of the venue, which I did not expect. All the other food and drinks sold inside is overpriced which is not surprising. It is entirely cashless inside the facility.
Most countries do not require (or is not possible to make) a reservation for entry to their pavilion. If you are someone that does not like getting in a queue, this event is probably not for you! I did see a few people that brought a small foldable chair and I thought that was very smart.
I visited the popular Chinese pavilion at 8pm with only a 10 minute wait. There is a water fountain show at around the same time, so this might be an opportunity when the lines get shorter. It does seem like there is some good strategy necessary to maximize your day at the Expo, particularly to fulfill your limited chances with securing advance slots for pavilion entry. Even then it is impossible to see everything in a day.