The Sectio Worm is a Mirror Monster and an antagonist in Kamen Rider Ryuki.
Kamen Rider Ryuki
GuldThunder devoured Yuichi after Yuichi turned down Shiro Kanzaki's contract offer. Kanzaki later ordered GuldThunder to go after Kamen Rider Raia, only for it destroyed by Raia's Hide Venom.
Kamen Rider Decade
Kamen Rider Wizard
GuldThunder was one of the monsters in the world within the Magic Stone. It was part of the group of monsters sent by Amadum to capture the boy and girl carrying the Rider Rings only to be confronted Kamen Riders Wizard and Beast, who attempted to take the Rider Rings to prevent the monsters entering the world. The boy then summoned Hibiki, Kiva, Den-O, Kuuga, Agito, and Blade to fight both the monsters and Wizard and Beast. GuldThunder and the other monsters were later finished off by Kamen Rider Gaim after he heard the children's cries for help and destroyed the monsters.
Powers and Abilities
It can attack with its retractable tail and use fire attacks.
It was originally designated to be the Contract Monster of Yuichi in concept arts in the event that Yuichi accepted Kanzaki's offer.