When they say it's rainy season in Japan in a certain months, do they really mean it? Will it rain buckets?

I'm not sure what to expect weather wise. Shall I bring my raincoat and leave a good pair of shoes at home?

Rainy season (tsuyu) is normally mid-June to mid-July. May isn't in the rainy season and it's in fact a wonderful month to be in Japan, warm (highs of 70-80F) and usually sunny. Rain is always possible, but not torrential rain. I'd just bring an umbrella, or buy one in Japan when needed - virtually every shop puts out cheap umbrellas (100-300 yen) when it starts to rain, and most hotels rent out umbrellas for guests' use.

When I was in Tokyo & Kyoto two Mays ago (2006), I experienced a day and a half of drizzly weather in each city. Not a torrential downpour, as one might expect in Singapore. More temperate, as one would expect in New York, or perhaps Paris.

Konichiwa, Alec and easywalker, thanks for your input. I will dress accordingly, and bring/steal/borrow an umbrella! May sounds like the perfect time to visit Tokyo.