Generally the modern Japanese music scene can be divided in two parts: yogaku 洋楽, Western style music, and hogaku 邦楽, Japanese music which covers Japanese traditional music and modern popular music composed by Japanese artists, so called J-Pop as well. Many Japanese enjoy karaoke カラオケ, a form of amateur performance in small nightclubs, singing enka 演歌 which has its root in medieval Japanese music.
The early chronicles describe music and dance as having been born together, as part of the successful attempt to coax the Sun Goddess Amaterasu out of hiding. Practical knowledge of music making before the 8th century CE, however, depends almost exclusively on archeology, although a 7th century Chinese historian noted that in Japan 'for music there are five string zithers and side-blown flutes' and a number of passages in the Kojiki 古事記 and Nihon shoki 日本書紀 remind us of the extensive musical interaction with the continent. The Nihon shoki states that for the funeral of Emperor Ingyo 允恭 in the 5th century, the king of Silla on the Korean peninsula sent 80 musicians who danced, sang and played stringed instruments en route to the capital.
The information for the 8th and the 9th centuries comes from the musical instruments that are miraculously preserved in the Shosoin 正倉院 imperial storehouse at the Todai-ji 東大寺. The collection, mostly gifts from the Chinese court, contains the ancestral forms of many present-day instruments .
Introduction of Buddhism and Chinese culture including the administrative systems together with continental musical instruments brought about an profound change in Japanese music.
The representative music of this period was Gagaku 雅楽, court music consisting of Chinese, Korean, Indian and native music. Shomyo 声明, Buddhist chanting, which had its beginning in India was introduced through China, and formed another major variety of music. While both Gagaku and Shomyo were modified to suit Japanese taste, they kept their original style to a remarkable extent, and two new major kinds of music of quite a national nature appeared in the early middle ages. These were Hiekebiwa 平家琵琶 in Kamakura 鎌倉 period (1192-1338), and Noh 能 in the Muromachi 室町 period(1338-1573). Heikebiwa was new and unique, and was to be the origin of narrative music. This is one of the most important and specific styles of Japanese music . The music of the Noh theater descends from both Shomyo and Heikebiwa.
During the second half of the 16th century Japanese encountered the European music together with musical instruments through missionaries and merchants. However, when rulers of Japan banned Christianity, it declined and was soon and forgotten.
The Edo 江戸 period (1600-1868) saw the emergence of three important instruments: Koto 筝, a long zither-like instrument with 13-strings, Shamisen 三味線, a three-string plucked long necked lute, and Shakuhachi 尺八, a vertical bamboo flute. The Koto is unique in that it was the first instrument for accompanying songs as well as a solo instrument in its own right. In the middle ages of Edo, these three instruments were held in great esteem, while the older music of Gagaku, Biwa, and Noh was also still in favor.
During the Edo period there appeared a new style of dance Kabuki 歌舞伎, which later became a kind of theater. Kabuki was often accompanied by Nagauta songs with a Shamisen orchestra. Another form of Japanese theater is the puppet theater, known as Bunraku 文楽 or Ningyo Joruri 人形浄瑠璃. This traditional puppet theater also has roots in popular traditions and flourished in the Edo period. It is usually accompanied by recitation Joruri and Shamisen music.
Japanese folk music is extremely varied from Ainu songs in Hokkaido to Ryukyu 琉球 music in Okinawa. Although historical evidence is elusive, many of the ritual and festival music of rural Japan are clearly of ancient lineage.
Following the Meiji restoration (1868), the traditional music began its decline. A Western based school music education system virtually ignored traditional music in the curriculum. Japan has been enthusiastic over Western music, both classical and popular up to present.
Today in Japan it is possible to hear a wide range of traditional music, any type of Western music, hybrid forms such as the popular enka songs of karaoke fame, and even a variety of other world music .
Gagaku, literally meaning 'elegant music' was established in the court around the 8th century CE, and has been preserved at the Imperial Court and in Shinto shrines and even some Buddhist temples. Gagaku repertory today consists of four following categories:
Gagaku in its present form represents the system which was established in the early Heian period (the beginning of the 9th century). This is a modification of the Gagaku of the Nara period (710-784), which was almost an exact imitation of the contemporary music of China and Korea .
The Gagaku ensemble Kangen usually consists of the following instruments:
Fig. 1. Ryuteki. An illustration from 'Gagaku-shu 雅楽集', 1894.
Fig. 2. The notation for Ryuteki 'Etenraku 越殿楽', a manuscript.Hichiriki 篳篥, a tiny oboe with a bamboo pipe having 9 finger holes, 7 on the front and 2 on the back. A thick double reed is inserted into the top of the pipe. The range of notes is g - a'. By controlling the reed the notes can be raised or lowered by a half tone or less.
Fig. 3. Hichiriki. An illustration from 'Gagaku-shu 雅楽集', 1894.Sho 笙, a mouthorgan consisting of a wooden wind chest which is covered with a plate, made of water buffalo horn. 17 thin bamboo pipes are inserted through the cover. At the lower end of each pipe a metal reed, like a harmonica reed, is fixed except in two pipes which are mute. The instrument is blown through the mouthpiece fixed to the wind chest. Sho produces the 11 given chords. The structure of these chords has not been solved definitely, however, several characteristic features could be noted: firstly, chords include the discord of a' and b', and secondly, each chord seems to be based upon the cyclic rotation of the fifths or fourths.
Fig. 4. Sho
Fig 5. The notation of 'Etenraku' for Sho and Koto (manuscript)
For Korean originating dance music Uho Bugaku 右方舞楽 there are special instruments such as:
We can see the original instruments for Gagaku among the collection of the storehouse Shosoin where 18 kinds of instruments of the year 752 have been preserved (http://shosoin.kunaicho.go.jp/). Pictures of Gagaku instruments and sample sounds are, for example, at the site http://www.gagaku.net/Gakki/index.html (Japanese)
The term Shomyo comes from the Chinese word Sheng-ming which stem from the Sanscrit, 'Sabdavidya', meaning a course of study for linguistics, rhyme and vocalization. This was one of the five major courses of study of Brahmanism, the prototype of Buddhism. When Buddhism was introduced to Japan, Buddhist chanting was called Bonbai 梵唄, the Japanese pronunciation of the Chinese Fan-pei, literally meaning pure chanting.
The history of Buddhist chanting in Japan began with the introduction of Buddhism around 522 BE. However, Shomyo which has been preserved until today had its beginning in the Heian period when two Japanese priests, Saicho 最澄 and Kukai 空海, brought Chinese chants from the mainland and established the Tendai 天台 sect and the Shingon 真言 sect respectively. These two sects have been responsible for the major kinds of Shomyo we know today. The Tendai sect has its headquarters in the Enryakuji 延暦寺 Temple on Mount Hiei 比叡 near Kyoto, and the headquarter of the Shingon sect was originally in the Toji 東寺 Temple of Kyoto, later moving to the Koyasan 高野山 Temple south of Osaka .
Buddhist chanting varies to a great extent according to the purpose and the sect. The language of the text can belong to three major groups: Sanscrit, Chinese and Japanese. The tone system also varies. Some have a seven-tone mode, others a five-tone mode, and then there is a specific modal style based on the nuclear tone system similar to that of the Noh. Actually Shomyo influenced Noh and Heikebiwa to a great extent.
As an example, we can listen to a Tendai Shomyo 'Shichi 四智' in Chinese at the website http://www.hosenin.net/shomyo/sho1/index.html (Japanese).
Also see http://en.wikipedia.org/wiki/Shomyo.
Biwa has its predecessor in the ancient Iranian four-stringed lute, Barbat. It had journeyed eastward through Gandhara (Afghanistan), Khotan (Chinese Turkistan) and China, where it was called Bi-ba or P'i-p'a in present-day Chinese. On the other hand, the five-stringed Biwa, or Gogenbiwa 五弦琵琶, has its roots in ancient India and was introduced to China by another route through Central Asia .
The Biwa was used only as a member of the Gagaku ensemble in ancient time, it was an instrument to accompanying Buddhist chanting in the early Heian period. And later, at the beginning of the Kamakura period, a new type of Biwa music called Heikebiwa appeared. It was a music narrating the Heike Monogatari 平家物語, The Tale of the Heike Family. This is one of the most representative examples of historical literature of the period, telling about the rise and fall of the Heike family, the greatest household of aristocrats .
Wandering Hiekebiwa players known as Biwa Hoshi 琵琶法師 were very similar to minstrels in medieval Europe.
Over the centuries the Biwa has been subject to many modifications in construction. The modern Biwa, for example Chikuzen Biwa 筑前琵琶 which became popular during Meiji period, has 4 or 5 strings and 4 or 5 frets respectively. The frets are much higher than those of the Western guitar. Then strings are also set high. When a string is pushed between frets, the pitch of produced sound varies significantly according to the strength of pressure applied to the string.
Noh is a classical Japanese musical drama that has been performed since the Muromachi period (1336-1573). Together with Kyogen 狂言, a comedy or farce usually be performed between Noh dramas as an interlude, it evolved from various popular, folk and aristocratic art forms, including Dengaku 田楽, a praying dance for good harvest, and Sarugaku 猿楽 the roots of which can be traced back to Chinese acrobatics, Sangaku 散楽. The present-day form of Noh was established by Kan'ami 観阿弥 (1333-1384) and his son Zeami 世阿弥 (1363-1443) under the sponsorship of Shogun Ashikaga Yoshimitsu 足利義満 (1358-1408) in the 14th and 15th centuries. It would later influence other dramatic forms such as Kabuki or Bunraku.
The typical Noh drama is performed by two actors: Shite シテ, or the principal actor, and the secondary actor Waki ワキ. There may be additional actor Wakizure ワキヅレ. The play is accompanied by a chorus of 8 voices, but unison, and instrumental ensemble Hayashi 囃子 consisted of Fue 笛 (traverse bamboo flute), Kotsuzumi 小鼓 (two head shoulder drum), Okawa 大鼓 (two head side drum) and Taiko 太鼓 (floor drum).
Fig. 6. The text and notes of the Noh 'Kagetsu 花月' (woodblock print of 1650)
The Fue has seven finger holes and the intervals, as well as absolute pitch, are rather vaguely fixed, for instance, c# (closed), d#, e, f#, g#, a#, c', d#'. However, the delicate changing of intonation is more important than the melodic line fixed by strict intonation.
The singing Noh, called Yokyoku or Utai , developed its style from Buddhist chanting Shomyo. Along with such temple chanting, it has retained through the ages the solemnity and introspection that are associated with religious music. Its spare melodic style has carried the masterpieces of medieval Japanese playwrights over the centuries into the present time. For example, Yokyoku (along with karaoke and golf) remains poplar with some businessmen. Thus, Noh singing has found a place in the modern society as a social skill as well as an integral part of the theater 
The Koto music is called Sokyoku 筝曲. In the late 16th century a Buddhist priest in Northern Kyushu, named Kenjun 賢順 (1574-1636) composed the first song to be accompanied by the Koto. This new music was named Tsukushi-goto 筑紫箏, taking the name of the province where Kenjun lived. Then, a blind musician, Yatsuhashi Kengyo八橋検校 (1614-1685) of Kyoto learned Tsukushi-goto and created a new style of Koto music. His new style could be characterized by his scale called Hira-joshi 平調子 and Kumoi-joshi 雲井調子 based on the In-scale, while Tsukushi-goto used the Ryo-scale of Gagaku  (see Section 10).
The tuning of these scales are as follows:
A Koto player Miyagi Michio (1895-1956) tried to introduce the diatonic scale, triple rhythm and orchestral style, which Japanese traditional music had never used before. http://www.miyagikai.gr.jp/index.html
An example, 'Sekiheki no Fu 赤壁賦' by Nakanoshima Kinichi (1934) is in the site
The Shamisen, which derives from the Sanshin 三線, is a close ancestor from Okinawa and one of the primary instruments used in that area, which in turn evolved from the Chinese Sanxian 三弦. It is supposed that Shamisen has a common ancestor with the Middle Eastern rabab and the Indian sitar.
The Shamisen can be played solo or with other Shamisen, in ensembles with other Japanese instruments, with singing such as Nagauta, or as an accompaniment to drama, notably Kabuki and Bunraku (see the Section 8).
There are three tunings of the Shamisen with different <interval>:
Today, one of the solo Shamisen styles named Tsugaru Shamisen 津軽三味線 is popular within young Japanese. As an example, we can listen to the music played by Oyama Mitsumasa at the site http://www.tsugarusyamisen.com/main.htm (Japanese)
The Shakuhachi is an end blown bamboo flute with four holes at the front and one at the back. The standard length of 1.8 Japanese feet (54.5 cm) is found in the name of the instrument - shaku (foot) and hachi (eight).
Fig. 7. Shakuhachi
The ancestor of Shakuhachi with six holes was introduced from China to Japan in the Nara period (710-784). It was modified into the Hitoyogiri 一節切 with five holes in the Muromachi period. At the beginning of Edo period itinerant Buddhist priest Komuso 虚無僧 of the Fuke 普化 sect of Zen who were employed by Samurai began to use a 1.8 feet long Shakuhachi for their mendicancy.
The artistic Shakuhachi music was established by Kurosawa Kinko 黒澤琴古 (1710-1771) who composed new pieces based upon the repertoire of the Fuke Shakuhachi. At the end of the Edo period musicians of the Kinko school began to participate in the Koto ensembles together with Shamisen. The chamber music such as trios or quartets, or sometimes even bigger ensembles, for Shakuhachi, Shamisen and Koto is called Sankyoku 三曲.
Fig. 8. An anthology of short songs 'Kouta-shu 小唄集'.
A narrative music style from the end of the Muromachi period (16th century) 'Joruri-hime Monogatari 浄瑠璃姫物語' is known as the origin of a new music style Joruri 浄瑠璃 in which narrations and songs are accompanied by beating fun, later by Shamisen. At the beginning of the Edo period Joruri met the puppet theater and formed a new genre Ningyo Joruri 人形浄瑠璃, or known as Bunraku. Shamisen for Joruri is bigger than for Sankyoku. This bigger Shamisen is called Futozao 太棹 which can create powerful sounds in the lower range of scale, and fits the dramatic emotion. Takemoto Gidayu 竹本義太夫 (1651-1714), a master of Joruri narration, created Ningyo Joruri a big art form together with a story writer Chikamatsu Monzaemon's 近松門左衛門 works. Thus, his name Gidayu became a synonym of Bunraku music.
Joruri is also applied in Kabuki, another form of Japanese theater which is popular even in the West for the stylization of its drama and for the elaborate make-up worn by its performers.
Originally Kabuki was created by Okuni, a miko 巫女 of Izumo Taisha 出雲大社 at the beginning of the 17th century. She began a new style of dance drama. Female performers played both men and women in comic plays about ordinary life. The style was instantly popular, and Okuni was even asked to perform before the Imperial Court.
The style of Kabuki theater changed from the female Kabuki to the young male Kabuki in 1629, then in 1653 to the adult men's Kabuki which comes down to the present time.
The contemporary Kabuki theater is usually accompanied by Nagauta 長唄 and three kinds of Joruri: Gidayu, Tokiwazu 常磐津, and Kiyomoto 清元. The instrumental ensemble Hayashi 囃子 consists of a Fue (a flute), a Tuzumi (a side drum), a Taiko (a floor drum) and three kinds of Shamisen, Futozao (larger size) for Gidayu, Chuzao 中竿 (middle size) for Tokiwazu and Kiyomoto, and Hosozao 細竿 (small size) for Nagauta.
Japanese folk songs minyo 民謡 can be classified in four categories:
In minyo, singers are typically accompanied by Fue, Taiko and Shamisen. These instruments are sometimes played with virtuosity.
It is notable that the folk music of Okinawa has its own characteristic features in its scale (see Section 10) and an accompanying instrument, namely the Sanshin or Jabisen 蛇皮線, a pythonic-skinned three-string lute which is the direct ancestor of Shamisen.
As an example of an Obon song we can listen to Kawachi-ondo 河内音頭 from the Osaka prefecture performed by a young artist Yamanaka Ippei 山中一平 at the site
Another well known Obon music is the Awa Odori 阿波踊り at Tokushima 徳島 in Shikoku 四国. Hundreds thousand of Japanese come to join the festival in August every year. Its characteristic rhythm is often compared with the Brazilian Samba.
The traditional Japanese melody has basically a pentatonic scale. Therefore the Japanese melody sounds similar to the other pentatonic Asian melodies and even to the Scottish. However, the Japanese melody has different scales than the other.
The five note system of the Japanese music was introduced from China with Gagaku:
This China originated scale is called Ritsu senmpo 律旋法, the Ritsu mode. Another mode used in Gagaku is Ryo 呂, of which each note is higher perfect fourth than Ritsu. Both Ritsu and Ryo modes consists of the plagal conjunction of two tetrachords (T1) .
Four types of tetrachords appear in the traditional Japanese music, namely:
T1 Gagaku mode (Ritsu 律 and Ryo 呂): <major second> + <minor third>, for example, <c - d - f> - <g - a - c'>,
T2 Minyo mode: <minor third> + <major second>, for example, <c - e flat - f> - <g - b flat - c'>,
T3 Miyako-bushi mode: <minor second> + <major third>, for example, <c - d flat - f> - <g - a flat - c'>,
T4 Ryukyu mode: <major third> + <minor second>, for example, <c - e - f> - <g - b - c'>.
Furthermore, the mixture of these modes forms In sempo 陰旋法, the In mode, and Yo 陽旋法, the Yo mode, sempo. These modes have different tetrachords in ascending and in descending passages.
The In mode is used in the artistic music whereas the Yo mode appears often in the folk songs.
Almost all Japanese folk music have the binary measure. However, in many Japanese music, such as the Noh music, there is no definite rhythm.