Ai is a young woman who wakes up with no memories other than her name and a faint idea that she is a princess from another world. In her confusion, she wanders the streets of Shinjuku until she meets a young man named Kent. She is immediately drawn to his kindness, and eventually agrees to accept his offer of shelter. As Ai attempts to reconstruct her lost past, it becomes evident that she has a deep love for music and a singing voice that deeply moves everyone who hears her. However, enemies from Ai's previous world are chasing her, and she must quickly learn her part in a conflict between worlds that she cannot recall.