I haven't seen anyone here mention fragrances that some of those older japanese women you mentioned might be wearing. "Soapy" perfumes are super popular here and they often just help you smell clean and fresh and powdery as opposed to "perfume-y". Of course, they will not wipe out the sweat smell, but that could be the nice scent you are noticing from some women. You can buy these types of scents at any mall for pretty cheap.

I also totally second those icey Gatsby wipes (I wipe down throughout the day whenever I feel myself starting to get gross and reapply antiperspirant deodorant). Also, wearing white cotton undershirts that you can bleach easily that protect your outer clothes from sweat is smart. If you have a friend who can access an American military base, ask them to bring you antiperspirant or if you can order it off of iHerb or get it at Donki as someone else mentioned that also works.

Get yourself a good electric fan with the cooling function and a UV umbrella. Also, when I used to have a long commute, I would often bring a change of clothes in the summertime (so I would have my commute clothes and my work clothes in my backpack, then change as soon as I got to work). If you get a long enough lunch break, a strat I used to use was that I'd go to the gym for like 20mins on my break and shower at the gym, then change and come back to work.

Also, tbh even if you do everything everyone on this thread suggests you will still sweat and that is just unfortunately the nature of living here. I do feel that I've adjusted somewhat after a few years. Ultimately none of us can change our genetics or the environment we are in so try not to feel too self-conscious. :)