[1] As identical 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.

Emi and Yumi were born identical twins Hideyo and Tsukiko Ito on Tuesday April 1, 1941 in the city of Tokoname in Aichi Prefecture.

[5] 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.

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.

[6] They appeared in the United States on The Ed Sullivan Show on April 3, 1966, performing "Lover Come Back to Me".

[8] The pair retired from performing in April 1975, with a farewell concert tour running from March 21st-April 5th 1975, after Emi married fellow Nabepro star Kenji Sawada.