Sputnik Sweetheart by Haruki Murakami

Sumire is in love with a woman seventeen years her senior. But whereas Miu is glamorous and successful, Sumire is an aspiring writer who dresses in an oversized second-hand coat and heavy boots like a character in a Kerouac novel. Sumire spends hours on the phone talking to her best friend K about the big questions in life: what is sexual desire, and should she ever tell Miu how she feels for her? Meanwhile K wonders whether he should confess his own unrequited love for Sumire. Then, a desperate Miu calls from a small Greek island: Sumire has mysteriously vanished...