The Peanuts

 were a Japanese vocal group consisting of twin sisters Emi (, "Itō Emi") and Yumi Itō (, "Itō Yumi"). They were born in Nagoya, Japan in April, 1 1941. As monozygotic twins they had voices only slightly apart in timbre, which resulted in their singing together sounding like a solo artist utilizing double tracking or reverb.
Career.
While still in high school, the twins were discovered by a talent scout while performing at a night club. They were brought to Tokyo where they became the first clients for Watanabe Productions. In 1959, the Peanuts became a hit at the Nichigeki theater. That same year, they released their first recording, "Kawaii Hana" ("Cute Flower"). In their early years they sang Japanese covers of standards, foreign hits, and Japanese folk songs; then they began singing originals, written by their producer, Hiroshi Miyagawa, and such songwriters as Koichi Sugiyama and Rei Nakanishi. They were the first to perform "Koi no Vacance". 
The twins embarked on a brief acting career appearing as Mothra's twin fairies, known as the Shobijin, in the 1961 film "Mothra", and the 1964 films "Mothra vs. Godzilla" and "Ghidrah, the Three-Headed Monster". In the audio commentary for the DVD of "Mothra vs. Godzilla", it is noted that director Ishirō Honda recalled the Itos' professionalism. Though not primarily actresses, the twins were surprisingly skilled, learned their lines without trouble, and always worked on time, despite their busy schedule.
Trivia.
Emi had a mole near her left eye. To preserve their image as identical, Yumi would have a mole drawn near her left eye.
Foreign performances.
They appeared in the United States on "The Ed Sullivan Show" on April 3, 1966, performing "Lover Come Back to Me".
Unusual for Japanese singers at the time, the duo had success in Germany, as well as in Austria. In 1963 Caterina Valente was in Japan where the duo caught her attention. Valente invited them to Germany. On the occasion of the 1964 Summer Olympics in Tokyo, Michael Pfleghar produced the opening ceremonies, where both were also invited, and the musical director Heinz Kiessling produced German-language recordings with them, including "Souvenirs from Tokyo". In 1965, Pfleghar cast them in two other shows "The Smile in the West" and "Schlager-Festspiele". In total, they released eight singles in the German language between 1964 and 1967. In 1965 "Souvenirs from Tokyo" reached No. 18 on the Austrian charts and spent 2 weeks at No. 40 on the German Billboard charts. In 1967 "Bye, Bye Yokohama" spent 4 weeks on the Germany charts, rising to No. 30. In 1966, the duo also performed at the Olympia in Paris.
Retirement and death.
The pair retired from performing in 1975 after Emi married fellow Nabepro star Kenji Sawada. The duo is remembered most for its versions of European songs and for a handful of Japanese pop songs, such as "Furimukanaide" ("Don't Turn Around"). 
Emi Itō died on June 15, 2012, at the age of 71. Yumi died on May 18, 2016, at the age of 75.