Japanese people are great, if your polite and don't have expectations, you will be treated nice in return... just like every other country I've ever visited.

There are some people who don't like tourists, but they will just pretend you don't exist, so you can ignore them right back.

https://www.youtube.com/watch?v=QRIklga9IBQ

This video matches my experiences in Japan, people are curious, helpful, if you have a mission and purpose the whole world is open to you. Be interesting, dig into some small fun detail, history, mission and people will pop out of the wood work.

Try and match the overall body language and energy of the calmest people around you.

Japan’s big on people paying attention to one another and accommodating one another, without making a big deal out of it.

Tokyo’s got the best sidewalk flow I’ve ever seen.

Overall, be circumspect. Keep your eyes open and notice what everyone is doing. Don’t be boisterous or gregarious. Quietly respectful is your best approach.

You'll come across good and bad wherever you travel. When we travelled in Japan a few years ago we found pretty much everyone we dealt with was friendly and helpful. We didn't speak any Japanese.

I wouldn't bother renting a car unless you've got a specific plan for it - their public transit is excellent and will still take you out into the countryside if you want.