Jun Yoshihara from The Rock 'n' Roll Aids Production has very kindly provided me with more information about Nana Kinomi. I love that photo of her by the way. She looks so cool!
Her real name is Mariko Ikeda. Her father was a trumpeter of the Nichigeki-theatre orchestra. At the age of 15, she passed an audition, and debuted in 1962.
Nana released 24 EPs and 2 albums in 1962-1969. "I Love You" was included LP "Let's Go Nana" (1968) as Nana Kinomi & Leo Beats. After the 1970's, she performed in musicals to great success, and can still be seen on TV in Japan.