Tips and Activities to Beat the Summer Heat in August - Osaka, Okinawa, Tokyo

Hi, I was wondering if there are any tips and alternate activities to beat the summer heat.

We've been to Japan before, specifically Tokyo and Kyoto during the spring season. We're well aware of the heat Japan is known for (we've been to South Korea in the same season - it was brutal), but unfortunately this is the only time we can travel.

Some tips I've seen already are: stay indoors during 12-4pm at the very least (and perhaps take naps during that time), and stay extra hydrated.

So, my questions:

- are there any recommended indoor activities we can do during the peak heat hours in Osaka and Tokyo, or even Okinawa? A few solutions I've come across for indoor activities are Round 1 in Osaka, and just going shopping (going in and out of shops that have AC). Any other recommendations?

- any specific japanese hydration drinks/hacks you guys recommend?

- I was wondering if faster transportation would be a good idea - instead of walking, we can do LUUP scooters or bikeshares in Osaka, for example. Any thoughts on this?

- we have mini-electric handheld fans that we're bringing. Any other gear/clothing recommendations besides hats that can help?

- In Okinawa we will be hitting the beaches mostly, and have AC in the car. Any tips for that region would be helpful though. We were thinking of just buying our own beach umbrellas and cooler-bags, for example.

Thanks!