The first child and a character shrouded in mystery, Rei Ayanami is an emotionally and socially disconnected girl with a notably quiet and reserved voice. Being often viewed as "a doll" by others, she shows no clear emotions in her presentation. She's very matter of fact in a soft-spoken way.
NOTE: If you're auditioning for Rei, I'd very much appreciate a take for Yui Ikari as well in a similar, more aged vocal direction. Thank you!