TOKYO — This is, if I have counted right, my 21st visit to Japan, but my first in August. I was right the first 20 times. Actually, I suppose August in Tokyo is not much worse than August in New York — or elsewhere in the Boswash corridor, for that matter. But those of us who live in the steamy purlieus between Boston and Washington are accustomed to think ing that it is just naturally hotter there than anywhere else outside the tropics. In this, as in so much else, the Japanese competition is stiff. The sun here is hot and strong, and even cloudy days are likely to be so stifling and humid that you feel like a damp mop by mid-afternoon. What’s more, the summer thunderstorms that often lash New York and Washington in August, bringing temporary relief from the heat, are much rarer here, I’m told. Luckily, Tokyo (or at least those parts of it a Westerner is likely to encounter) is comfortably air conditioned. New Yorkers will be especially interested to hear that this even applies to the neat and crime free subways — and not only to the trains, but also to the positively breezy stations. Mayor Koch, take note. (BU) The yen has appreciated 40 percent against the dollar in the past 10 months, and that makes buying anything in Tokyo these days an almost surreal experience for an American. Luckily, the yen as a unit is so small that all prices are express ed in figures that are ridiculously high to the American eye anyway, so paying them is painless, unless you take the time to factor in the conver sion rate. At this writing, you can get about 151 yen for a dollar. Now, I’ll admit that I will be talking about prices in hotels in Tokyo’s modern, distinctly upscale Shinjuku district; I’m sure one could do a bit better in second class hotels. But you know, and I know, that comparison shopping even in your own hometown is often tedi ous; in a big foreign metropolis it is usually out of the question. OK, so you'd like a modest break fast sent up to your hotel room? Keep it really modest: just orange juice, two slices of toast and coffee. That’s 750 yen for the juice, 400 for the toast and 700 for the coffee. Add 10 percent for service and as much again for the tax, and that’s 2,220 yen — or about $14.70. A bottle of Japanese beer in that cocktail lounge downstairs will set you back 600 yen ($4). If you decide to try a sukiyaki lunch in the hotel’s Japanese restaurant and recklessly wash it down with a couple of bottles of that beer, that'll be $80, thank you for a party of one. Even the airport tax is 2,000 yen, or $13.25. If you buy a copy of Time magazine to read on the plane, there go another four bucks. If it’s any consolation, this ridicul ously high rate of exchange is hurting many Japanese too. Most obviously damaged are Japan’s export compa nies, 72 of which went bankrupt in July alone — a record for the fourth consecutive month. Who would buy anything Japanese? (BU) While I’m at it, let me pause here to pay my annual backhanded tribute to the International Herald Tribune, the English-language daily edited in Paris and published all over the world. Owned jointly by The New York Times and The Washington Post, it relentlessly reprints the left most articles and even cartoons from both of these noted propaganda mills, and thereby probably does the United States more affirmative damage, week after week, than the entire Overseas Department of the KGB. There is not a U.S. government policy it doesn’t knock, without any effec tive rebuttal whatever. When a bigger disgrace is engineered (and it’s hard to imagine one), the Times and the Post will no doubt be in ‘on it. William Rusher is on a tour of East Asia sponsored by the World Media Association, a group associated with the Rev. Sun Myung Moon.