Most Japanese rarely move their hands while speaking, unlike, say, Italians, who have codified many of their hand-gestures into specific meanings and use them frequently in everyday speech.
In Japan the only such codified hand gestures that come to mind are the right index finger pointed at the nose to signify "me" as well as the Churchillian "V" or "Peace Sign" ubiquitous on group photographs of preening teenagers and 20 somethings and, of course, the rock, paper, scissors game (jan ken poi).
The world of advertising in Japan is another matter and hand and finger gestures are used extensively. Next time you look at the advertising on the Tokyo subway or glance at an election billboard with the smiling face of a politician, look at the hands.
For the politicians, a clenched fist is widely used to show strength and sense of purpose. In ads using a female Japanese model, look out for a tapering index finger pointing elegantly skywards or at the name of the advertised product.
Here in a recruitment ad for the police and fire service the Japanese model uses both erect index finger and clenched fist.
Japan has a reputation for manual dexterity: origami, using chopsticks to eat and the way the bank clerks count and spread bank notes come to mind, so I suppose all this fist pumping and index finger raising is a by-product of traditional Japanese ways of doing things.
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