Natsumi Hikari (光 夏海 Hikari Natsumi) is a young woman who works at the Hikari Photo Studio under her grandfather, Eijiro Hikari while traveling through the A.R. Worlds with Tsukasa.
Eventually, she becomes Kamen Rider Kiva-la (仮面ライダーキバーラ Kamen Raidā Kibāra, Masked Rider Kiva-la), a Kamen Rider appearing in Kamen Rider Decade: The Last Story. Similar to other riders in the series, Kiva-la is an original Kamen Rider with origins coming from an A.R. World. Though unlike them, Natsumi does not come from an A.R. World and only used her powers twice