Misa recognized him the moment she saw him. She'd
met him when she was very young, in a park. She'd thought he was odd, then,
and it seemed like things hadn't changed.
She was intrigued by why he had given her a different name then the one she saw floating over his head. It was only when she caught the look in Light's eyes that she realized that this was L, the detective that was tracking Kira.
And, as the second Kira, she knew what her duty would be. For Light, the first Kira whom she loved, he would die.