You have probably never heard of the demoniacally named Driclor before. It's a roll-on treatment for hyperhidrosis, or excessive sweating. It works. Unbelievably. If you use it for a couple of weeks, you will not sweat in the applied areas. This is perfect for the viciously hot and humid Japanese summers.
It's normally prescribed, but is available without a prescription. Read on for how to get hold of some in Japan.
I have never found this for sale in Japan, but UK and other nationality companies will ship internationally. I recommend Expresschemist.co.uk, where you can also buy your toothpaste or other toiletries you are missing in Japan. One roll-on will set you back about 4 pounds, and postage to Japan about the same.
You can also buy from Amazon.co.uk for a similar price.
Apply before bed and wash off in the morning. Expect to be eternally grateful for it.
The active ingredient of Driclor is aluminium chloride hexahydrate. This itself is harmless, although in can be broken down into hydrochloric acid. This doesn't affect the end result, but can lead to irritation shortly after applying the roll-on. It goes away and isn't strictly bad for you, but can be a bit irritating (get it?). Other than that, Driclor is side-effect free.
The downside is, of course, you need to apply it to most of your body during the summer. Can't win them all.
There's also a product called Anhydrol Forte, which does the same job. I have no experience with that one, however.
I wish you the greatest happiness when you realise you can wear whatever you like this summer, without worrying about sweat patches.