Who is Joanna Rand/Lisa Chelgrin from The Key to Midnight and what is their importance?

Joanna Rand is a lounge singer, who owns a nightclub in Kyoto Japan called Moonglow lounge. Joanna is young, single, and attractive, drawing the attention of the many customers of her club. One customer in particular, Alex Hunter, is fascinated by Joanna, drawn to her voice as much as her subtle beauty. When Alex asks Joanna to lunch, she surprises even herself when she accepts. Joanna and Alex hit it off from the first moments, so well in fact, Joanna agrees to take Alex on a guided tour of the city. However, while touring an old castle, Joanna has a panic attack that is eerily like a recurring nightmare she has suffered for years. By this time, Alex has realized why Joanna looks so familiar to him, coming to the conclusion that she is a missing woman from the United States he spent nearly a year looking for over a decade ago.