You may be tempted to buy a Japanese T-Shirt because it might look cool to walk around with flashy kanji or hiragana on your body -- you'll look worldy and sophisticated, after all. If you think that, just remember you could be wearing something you don't understand (just like all the Tokyoites with their Englis-language shirts, which is another tip in itself).
I made this mistake by purchasing Julia a cute pink Japanese T-shirt on a previous visit. Thinking it would be fun, she wore it around Tokyo all day on the first day of our August 2009 trip. We had no idea what it said, but it had penguins and hearts on it, so how bad could it be?
After roaming around Tokyo, that though popped in my mind, so we asked the bilingual concierge upon our return. I began to worry when he turned red and refused to tell me in the presence of Janet and Julia. "Can you write it down?" I asked.
He wrote down two words, which he showed me under an uplifted hand, out of the girls' view: "Love Hotel"
Love Hotels are places in Tokyo that rent rooms by the hour so cheating couples and other illicit lovers can spend alone time together. Not, according to the concierge, the kind of thing that an 8-year-old should be advertising! Janet and I had a good laugh, though we'll probably not let Julia ever where that shirt around Waikiki again!
Most of the Japanese are very shy and polite, must avoid using rude words or aggressive words like `fu*king', other than this, in Japanese alphabet `H' consist of make love. Most of the young people are sensitive with it. So, French, you are saved here, always no `H' in mind.