The term Enka (演歌）was originally used to refer political protest songs from the late 19th century.
First used in the contempory sense in the mid-1960s, the term was used to denote music that combined Western melodies, instrumentation and notation with Japanese style vocalization and rhythms, often using a pentatonic scale.
The style developed in the late 1930s, and was influenced by Scottish, Irish, Italian and Russian folk melodies, chanson and big band, as well as drawing on Japanese musical traditions.
The popularity of artists like Misora Hibari starting in the 1950s solidified it's place in Japanese popular music, especially for older listeners.
The genre's popularity started to wane in the 1970s as rock and Western style pop became more popular, though some artists like Hibari had hits into the 1980s and beyond.
Basically Enka must be minor melody song that made without the scale of the "Fa" and "Si". The Western scale is seven scales. However, the Japanese scale is five scales. The Japanese scale "ヨナ抜き" (Yona-nuki : "Yo" means 4, "Na" means 7, "Nuki" means Without) It without using 4 "Fa" and 7 "Si".
Enka and J-pop can not coexist on the same genre.
Archetypal enka singers employ a style of melisma—where a single syllable of text is sung while moving between several different notes in succession—known as kobushi. Kobushi occurs when the pitch of the singer's voice fluctuates irregularly within one scale degree; this compares with vibrato, which vibrates in a regular cycle.
The kobushi technique is not limited to enka, as can be heard in the Italian song "Santa Lucia."
In the late 1930s and early '40s, the music of composer Masao Koga began to resemble Buddhist shomyo-chanting possibly because his record label asked him to produce music.
Although Koga became a composer whose work is considered seminal to the creation of the genre, present-day enka is different from Koga's primary music because the singing styles of many postwar singers were different from the kobushi of Koga's musical note.
Japanese RCA made Enka campaign in early 70s. That's because Crown records appeared to be a special label for Enka's release. But Crown records had certainly expanded terms to make Enka popular.
For the release of Sakariba Kayō / Sakariba Pops and Mood Kayōkyoku (Moody Kayō) they credited Enka. RCA records used Keiko Fuji and Cool Five as image singer for their Enka campaign. RCA used them as their strategy to expand the Enka market. However They were not Enka. Enka's term was expanded by their strategy and business war, so even many Japanese have obscured the category of Enka at that time, And that then made their misunderstandings for Enka category.
Also Japanese economy improved in the late 1970s to mid 1980s, duet songs, pop songs and banquet songs sung in the amusement quarter were in great demand. It's called Sakariba Kayō / Sakariba Pops. It has a close relationship with the spread of Karaoke.
To be exact, They were not Enka. Even early Meiko Kaji was not Enka. They sang the dark kayō which Enka fans wanted. Keiko Fuji was singing Enka fans' favorite song style and her song was not on the Enka term made by Masao Koga. But like Kaji Meiko, Keiko Fuji also became Enka singer at late 70s.
Also Enka is a solo style. Enka can not sing in groups.
Because Enka has no back chorus or back singers. It will be Mood Kayōkyoku (Moody Kayō) and It belongs under Shōwa Kayō.
Of course Sakariba Kayō / Sakariba pops which are singing on the duet. It is not Enka. It will be Duet Kayōkyoku (Duet Kayō) and It belongs under Shōwa Kayō.
Westerners tend to confuse Japanese dark folk song and Enka. Solo singers singing while playing acoustic guitar in the late 1960's to 1970's in Japan do not mean Enka. They are Nagashi singer. Nagashi does not necessarily need to be Enka, but they sing in response to customer requests at dark spot and bar. At the time it was demand that only dark and sad songs reflect Japanese society. Before karaoke became popular, people in the amusement district needed Nagashi. Nagashi was singing dark Kayōkyoku and sentimental Enka that they requested. This is a part of Shōwa Kayō ' history.
There are other factors in the Enka term that makes Westerners stray.
This is like a word play in Japanese. Kanji has 音読み (On Reading / Chinese Reading) and 訓読み (Kun Reading / Japanese Reading).
艶歌 and 怨歌, both of which are read as Enka. Enka (艶歌) 艶 is "Tsuya" Sexy, fascinatingly that only women have voluptuous or bewitching feeling.
If use this kanji Enka (艶歌), it means sexy Kayō even if it is not Enka (演歌). Enka (艶歌) often has not Kobushi vibrato. Enka (怨歌) 怨 is "Urami" Resentment or umbrage. Fame as Meiko Kaji's 怨み節 Urami-Bushi.
Enka (怨歌) has heavy Kobushi vibrato like Monzetsu Kayō (Monzetsu = Faint in agony). 艶歌 and 怨歌, These two Enka expressions from vocal style can be used for all music categories. There has another Enka (援歌 = Cheer song) like Kiyoko Suizenji's "三百六十五歩のマーチ" This is a female Enka singer sang cheer song in March style. To be exact, It's not 演歌 (Enka).
Western users think that emotional ballad with vibrato are Enka style,
but that is a big mistake.
Enka has its own structure and technology. It is described above.
Protest campaign by young people in Japanese riot era (Japan - US Security Treaty, Vietnam War, The Cold War, Narita Conflict etc) The coined word used to gain the support of young people by Japanese B-movie was a 怨歌 (Enka. 怨 is "Urami" Resentment or umbrage) Through this, Yakuza Movie and pinky violence films appeared by 梶芽衣子 and 三上寛 and such image singers sang dark grudge song, and major Japanese record companies have abused these coined words to expand the 演歌 / Enka market. To be exact, These were not 演歌 (Enka).
They wanted to expand the 演歌 / Enka market using frustration of young people and they wiping out the image of old Japanese traditional enka.