The Japanese accent refers to a variation of pitch patterns within a word. For example, in the standard language, which is based on the Tokyo dialect, bridge is pronounced as はし hashi 橋 （bridge） with the ha low and shi high in pitch remains; whereas , chopsticks also being pronounced as はし hashi 箸 (chopsticks)but with the ha high and shi low in pitch. In other words, accents make a difference in the meaning of words.
Moreover, the characteristic for accents in standard Japanese is that the second mora of a word always has a different pitch from that of the first mora. In other words, if the pitch of the first mora is high, the second will be low; if the pitch of the first mora is low, the second will be high.
The normative Japanese accent can be divided into two categories, namely the unaccented and the accented. For words from the unaccented category, only the first mora is low in pitch, the following ones are high and remain high until the end of the word. The pitch does not fall drastically in unaccented words.
For words from the accented category, there is a place in the word where the pitch of the sound falls drastically. This place is called the accent nucleus. There is only one accent nucleus in each word. For instance, in the case of はし hashi (chopsticks), the pitch falls right after the ha sound, thus we say that the accent nucleus is at ha , which also happens to be the first mora of the word. For words that have their accent nuclei on the first syllable, we call them the initially-accented words.
In あなた anata (you), there is a drastic fall in pitch after na , and so the accent nucleus is on na . We call words with this type of accent the middle-accented words. Words such as みずう mizuumi 湖 (lake) andなつやすみ natsuyasumi 夏休み (summer vacation) are also middle-accented words. The accent nucleus is on u for mizuumi (lake) ; whereas , for natsuyasumi (summer vacation), it is on ya .
In addition, for accented words there are cases where the accent nucleus falls on the last mora. We call words with this type of accent the finally-accented words. When pronouncing a finally-accented word by itself, where there is no drastic fall in pitch within the word, it will sound as if it is an unaccented word. The difference between unaccented and finally-accented words will only surface when particles are attached after the word. For example, the pitch of 、 はなが hanaga 鼻が (nose + particle)is Low-High-High, and thus hana (nose) is an unaccented word. For は なが hanaga 花が (flower + particle),the pitch is low-high-low. In other words, there is a drastic fall in pitch after na , so hana (flower) is a finally-accented word.In order to master Japanese accents, you must be able to grasp the position of the accent nucleus for each and every word you hear.