A bright and energetic third-year student at Furasu High School. After getting caught up in an incident where Chemys were released from Ride Chemy Cards, he is tasked with the mission to retrieve them by transforming into Kamen Rider Gotchard. He transforms using the Gotchardriver and Ride Chemy Cards, and can access enhanced forms by equipping additional units like the X-Gotchalibur, Gotcha Igniter, Tenliner, and Nijigon. He rides Golddash and is close friends with the grasshopper Chemy, Hopper1, and the locomotive Chemy, Steamliner.

Hotaro's classmate who appears to be a well-behaved, top-tier student, but her true identity is an alchemist belonging to the Alchemy Academy hidden beneath Furasu High School. She harbors complex feelings regarding her father, Fuga Kudo—a brilliant alchemist who, ten years ago, suddenly disappeared and was suspected of stealing the Academy's Ride Chemy Cards and Gotchardriver. She transforms into Kamen Rider Majade using the Alchemisdriver, High Alchemist Ring, and Fantastic/Cosmic Chemy Cards. By using the Promise Alchemist Ring on her left hand to change the Alchemisdriver into the Majesty Driver, she transforms into Twilight Majade with the Twilight Chemy Card.

A graduate of the Alchemy Academy and a Super A-Class Alchemist dispatched by the upper management to retrieve the Chemys. He transforms into Kamen Rider Valvarad using the Valvaradriver and two Chemy Cards of the same level. By changing the Valvaradriver into the Valvaradriver Kurogane with silver flames, he transforms into Kamen Rider Valvarad Kurogane using Metal Chemy Cards.

A history teacher at Furasu High School, where Hotaro attends, and a teacher at the Alchemy Academy beneath the school. While he usually appears indifferent, he shows a cool and mysterious side when he dons his alchemist's cloak and acts in his true profession as an alchemy instructor.

The mentor and superior who supports Kurogane Spanner.

An intellectual alchemist in the same alchemy class as Rinne. Due to extreme social anxiety, he communicates through 'Isaac,' a sharp-tongued AI built into his tablet. Surprisingly, he shares Hotaro's love for Chemys. He is long-time friends and a comedy duo partner with his classmate, Renge Icho. As a knowledgeable supporter regarding Chemys, he shows steady mental growth. He uses Isaac's interpretation to voice his opinions and plays a supporting role by creating equipment to charge Alchemist Rings so that Rinne does not run out of transformation energy.

An alchemist from the Kansai region in the same class as Rinne. She studies alchemy to create gold and provide a comfortable life for her mother... though seeing her try to sell Chemys to Hotaro suggests she might just be a miser. She is long-time friends and a comedy duo partner with her classmate, Sabimaru.

Rinne Kudo's father. Originally a brilliant alchemist of the Alchemy Academy, he realized ten years ago that enemies were targeting the power of the Ride Chemy Cards. To stop them, he fled with all the Chemys stored at the Academy and the Gotchardriver he had synthesized. However, because he acted alone without revealing the truth to anyone, the Academy branded him a traitor. He transforms into Kamen Rider Wind using the Alchemisdriver, High Alchemist Ring, and the Black Bahamut and Kuroana (Black Hole) Chemy Cards.

Lachesis: The youngest of the Three Dark Sisters. She uses alchemy activated by the sound of a Jew's harp and uses a sword in combat. Clothyo: The middle sister of the Three Dark Sisters. She is skilled in hand-to-hand combat and is highly bellicose. Atropos: The eldest sister of the Three Dark Sisters. She can use powerful alchemy by blowing her breath into a transparent diamond-shaped weight.

Geryon: The one who created the Three Dark Sisters. He transforms into the golden Kamen Rider Eldo using the Eldoradriver and the Eldoragon Chemy Card. Gigist: A mysterious being known as a King of Dark Night who was sealed within the Door of Darkness in the Ouroboros Realm. He specializes in spatial alchemy that far transcends forbidden arts, believed to be derived from divine techniques. Gaeliya: One of the Kings of Dark Night, a mysterious being sealed within the Door of Darkness in the Ouroboros Realm. She established a unique ritual system using alchemy and astrology, seeking answers for all phenomena in the movement of the stars. Germain: One of the Kings of Dark Night, a mysterious being sealed within the Door of Darkness in the Ouroboros Realm. A progenitor-like figure to alchemists, he boasts a level of skill that allows him to create organic matter from inorganic matter. He believes that all of humanity becoming Malgams is the correct evolution for humans and Chemys, and seeks to reclaim the Chemys.