Japan in July-Aug advise

Hi,
Trying to plan on when would be best to leave for Japan for a planned July-August visit this year.

I have been checking out information on several festivals, and I learned the school holidays begin around 18th of July.

I cannot stay longer than 15th of August due to work. I plan to leave somewhere between 10th to 20th of July, staying for 3,5 weeks mostly around Chubu, Kanto and Tohoku area.

What is the question?

get ready to sweat a lot and occasional thunderstorm.

It will be very hot and humid except in Hokkaido and most northern parts of Honshu. Decide if you are fine with that.
And yes, agree with PP, what is the question???

Enjoy planning your trip to Japan!

I think the question is the best time to leave between 10 and 20 July, having regard to holidays etc. I've never been there at that time, June and September have been hot enough for me.

Ah, yes, the question was when would be best to leave, unless it makes no big difference.

If the schools are emptied in the mid of July maybe it does not matter when I go since I will be in Japan most of the time by then.

I aim to visit the "highlands" most of the time to get away from the heat.

I plan to visit the Neputa festival or the one in Akita in early August possibly.