I interviewed our English teacher in 2012. She is a Japanese women. I asked about such as that she is careful when she go to a foreign country to her. Then, she gave me 4 answers.
First, she doesn't stand her thumb to her because it is equivalent to an insult.
Second, she starts from her thumb to her little finger when she counts on her fingers. It avoids causing a misanderstanding. I hear agesture which expresses"two" is resembled to a gesture which expresses killing or death in the wartime.
Third, she doesn't point to anyone with her forefinger to avoid causing amisunderstanding of her gesture that stands her middle finger. To stand midlle finger is equivalent to an insult.
Last answer is she is careful to not offer her hand to a person thoughtlessly. To our surprise, I hear people don't make contacts frequently in some country especially women.
I thought Japanese are not care of their gesture compared with another country.