Natsumi Hikari is a young woman who works at the Hikari Photo Studio under her grandfather, Eijiro Hikari while traveling through A.R. Worlds with Tsukasa Kadoya, also known as Kamen Rider Decade. She eventually transforms into "Kamen Rider Kiva-la in Kamen Rider × Kamen Rider W & Decade: Movie War 2010".

When annoyed, she tends to use the "Laughing Pressure Point" (a swift strike with her thumb on the neck pressure point) technique on the person who annoyed her.