I’m sorry you received such an unpleasant initial first response.

I’ve personally managed to completely avoid visiting during the rainy season and will continue to avoid it, but I have had a few tastes of what it can be like during May and July visits. I also once came across a traveller during a rainy period in August in Hiroshima who was an assault to the senses. The guy absolutely reeked and my husband explained that this was the stench of someone who hadn’t dried out his clothes and that it takes very little time for this kind of smell to set in and stay when living in Japan during the warmer months.

Looking at your itinerary Jetsetpensioner and seeing that you are staying at higher end hotels, your laundry needs are actually going to be harder to get attended to than someone going to more modest accommodation with dedicated washing and drying facilities (I just spend a few days in the Sunroute Taipei - where humidity is a an ongoing reality - and received complimentary access to their machines).

Even if you aren’t challenged by your daily plans (you are being very ambitious) it’s hard to see where you will have the time for self-care for your clothing. I guess one solution will be to have your hotels take care of it for you, if so, take account of those costs as they will be significant. Otherwise, set aside some time to visit a coin laundry or find an affordable wash and fold service. Your hotel concierges should be able to point out where they are, just remember that this will take a sizeable chunk out of your visit. If you send damp clothes via takkyubin you might never be able to use them again.