The rainy season is upon us in most parts of Japan. It is called “baiu” or “tsuyu,” which literally translates as “plum rainy season” — so-called because plum get ripe around this time of the year.

While the name is rather exotic, it is the month when we have so much rain. Because of that, June is not the ideal month for tourists to visit Japan. Two other months I strongly recommend avoiding are July and August as it is so hot and humid in Tokyo — though there are some places like Hokkaido that are spared from the rainy season and remain comfortable.

Even though this may not be the ideal month to visit Japan, tourists from overseas might find people’s behavior here rather interesting. That is, how so many people carry around umbrellas.

Visitors from the United Kingdom might not give a second thought to the number of umbrellas. But North Americans may be surprised to see this rather unique behavior and wonder what is going on.

I first noticed that this behavior of Japanese may not be universal around the world when I saw quite a few people in the United States, for example, walking in the rain without umbrellas. They seemed not to be so bothered by it. I realized that what we take for granted as a custom in the country of origin may not be common practice elsewhere.

So, I tried to explore the background of this seemingly unique behavior in Japan. First, I started with facts. According to the Global Umbrella Study results, the number of umbrellas per capita in Japan is 3.3 — the largest in the world. The global average is 2.4.

Through further research, I hit upon several hypothetical reasons to explain the behavior. For example, one hypothesis is that the number of rainy days in a year correlates with umbrella-carrying behavior. If it rains a lot in the area, it is natural that people learn to carry around umbrellas. However, this hypothesis was rejected as Japan is ranked 13th in the world (with some 100 days) in terms of rainy days.

Another hypothesis centers on the duration of rain. As rain tends to persist (it often rains day in and day out with only a few clear days in June), people make it a custom to carry umbrellas, knowing that it will likely rain at some point in the day.

Another reason that sounded convincing was high humidity. Compared with many parts of North America and Europe, it is more humid in Japan and it does not dry out quickly after rain so people try to avoid getting wet even in a light rain. The number of people in Japan bothered by their clothes getting wet is 25 percent, second only to the U.K. at 39 percent.

Some interesting features in Japan regarding the umbrella sets it apart from other countries. In Japan, 62 percent of the umbrellas in use are the standard type and just 21 percent are the folding type, compared to 55 percent worldwide . Now transparent vinyl umbrellas account for 10 percent of the total in Japan because they are inexpensive (costing from ¥500 to ¥1,000) and are disposable. They’re particularly popular among the younger generation and make up about 25 percent of the umbrellas they own.

Over the past two decades, disposable umbrellas have been imported to Japan in large quantities, mainly from China. Their low price is one of the reasons for their popularity and the increased frequency of sudden downpours in recent years may also have led people to buy them. Umbrellas seem to have become such a low-ticket item that they may not mind misplacing or losing them. In fact, train conductors warn against leaving umbrellas on the subway on rainy days, indicating how often people forget them.

Another peculiar rain-related tendency of Japanese people is their frequency of checking the weather forecast — up to 3.4 times a day, which is 1.1 times more than the world average of 2.3 times a day. Some people argue that the frequency in which Japanese check the forecast and their wariness of rain are related to their almost universal behavior of carrying umbrellas. Whether this behavior points to the preparedness of the Japanese is unclear, but the theory sounds reasonable, as people here think of rain as a nuisance given the humid climate and try to avoid the inconvenience of suffering from the consequences.

The historical development of umbrellas in Japan is quite interesting. Umbrellas were first developed in the 8th century and the first Japanese-style folding umbrella was made during the 16th century. It used to be for aristocrats but became a daily item for ordinary people in the 17th century.

During the Edo Period, umbrellas became props for kabuki, Japanese dance and tea ceremony and formed an important part of Japanese culture. Accordingly, the artistic aspect of umbrellas were pursued in addition to the practical use. It was in the early 1800s that the Western-style umbrella was brought to Japan from the U.K., but their production did not begin until after the Meiji Restoration in the late 19th century.

Though the umbrella is a minor example, it teaches us at least two things. One is that observation is very important visiting new places. Noticing the differences between one’s own country and others, however small they may be, can be the first step to realizing that diversity exists. Noticing diversity leads to more questions about the backgrounds and reasons, which may help people become more aware and sensitive to different lifestyles. We talk about importance of diversity today, but tend to focus on gender, race, nationality, etc. Even small things such as umbrellas can lead to a new awareness of diversity found in cultures and lifestyles.

Today, there are at least two opposing views about diversity. One school of thought encourages people to appreciate diversity as it leads to constructive and healthy debate. The other is based on an intolerance of differences.

The latter may divide people into small worlds of their own where they confirm to their own beliefs and make little effort to see the differences and their potential.

Which view we take is up to us. It starts with paying attention to small differences such as umbrella-carrying behavior and an inquisitive mind to explore the reasons behind differences. People may not like the rainy season, but it can offer a key to better understanding how people act differently.

Yoko Ishikura is a professor emeritus of Hitotsubashi University and serves as an independent consultant in the area of global strategy, competitiveness and global talent. She is a member of the World Economic Forum’s Global Future Council.

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