Kamen Rider Larc is the alter ego of Natsumi Miwa. She first appears in Kamen Rider Blade: Missing Ace. Natsumi Miwa originally applied as an office worker, but was berated by the boss. As a result, she knocked him out after having enough of his words. She was handpicked, along with Shin, by Glaive to become the New Generation Riders for BOARD to capture the Undead released by the Albino Joker. She is armed with the L'arc Rouzer, a crossbow. H
er weapon is based on the Garren Rouser and the Chalice Arrow. Her primary finisher is Ray Bullet, a supercharged energy arrow. She was killed by the Albino Joker shortly after all the Category King Undeads had been resealed. Her rider name, "Larc", may come from the French words "l'arc" which means "the bow", being the replacement of Chalice, as well as Garren, for the team's long range fighter.
In Kamen Rider Decade, she was played b the same actress and had the same name, but she didn't appear in Blade World, but in the WOrld of Diend. Haruka Miwa is a young woman who resists Fourteen as Kamen Rider Larc. She took part in the operation to overthrow Fourteen and ended up escaping with Shin when the operation was a failure. Since then, she has been on the run from Fourteen's minions. She helps fill Tsukasa in on what is currently happening in her world.