Greeting, to them, is a sign of respect. The art of greeting is called "Aisatu," and it ranges from words such as "hello," and "good day" to bowing, known as "ojigi," which is the most formal sign of respect.
In many situations where handshakes are customary in English-speaking countries, bowing is used instead; even when they are aware that the other person cannot see them, people routinely bow. In Japan, being able to bow properly is seen as a sign of adulthood.
The Japanese revere greetings so much that they have over 10 different ways of saying hello. Their children are taught the right words to say and angles to bow right from an early age. The first years of kindergarten are dedicated to greeting etiquette and learning respect.