Ikadevil

Ikadevil (voiced by Tadao Futami) is actually Doctor Shinigami who's an executive member of Shocker from the Switzerland branch.

Before joining Shocker, Doctor Shinigami was known as Ivan Tawanovitch a half-Japanese, half-Russian citizen who was given the title 'Shinigami' due to the deaths of people he met, even if he did not have anything to do with the deaths and 'Doctor' after he graduated from college with a doctorate as a famous researcher.

Shinigami was working with the Nazis during WWII when Japan was allied with them. He was working on a way to make replacement bodies for dying people, one of them was his father but it was a failure. His sister had became ill and after an accident in the arctic her body was frozen. After the war, the doctor traveled the world after hearing rumors of a monk who can bring back the dead. After finding the monk, Chan Mao, in Tibet, the doctor begged the monk to tell him the secret of bringing back the dead. But the monk refused as the doctor because he is too bound to human emotions. A few years later, Shinigami finds Mao supposedly dead in South America, but Mao had actually just transcended his Earthly body. Mao then asks Shinigami to join him in his goal to take over the world offering to help save his sister.

Shinigami began working in modified human research in Europe, but his creations were destroyed by Kamen Rider #1 whose constant interference made the doctor focus on defeating the rider. After Colonel Zol's destruction at the hands of Rider #2, Shinigami takes command of Japan's branch.

He faces Rider #2 in Japan several times, and came close to success, but with the help of the original Rider, the Double Riders stopped his plans. Eventually he left Japan to South America only to be followed by Rider #2.

Shinigami then goes through a reconstruction process to become Ikadevil, a Squid monster with the ability to use his tentacles as whips and a pincer claw for his left hand. However, Shinigami predicts he will die in battle. He returns to Japan and works alongside Ambassador Hell to take down Takeshi Hongo.

Hongo confronts Shinigami as Ikadevil when he's ambushed while testing the New Cyclone. Frustrated by Rider #1's continuous interferences, Shinigami decides to attack him personally by kidnapping Tobei Tachibana and forcing him to train him to crush Rider #1. However, that just leads to Tobei noticing Ikadevil's weakness.

Finally, Shinigami challenges Takeshi Hongo to a duel. When they meet, Shinigami discards his cape and transforms into his inhumanoid form, Ikadevil, revealing his identity to Hongo. Shocker Combatmen take care of Kazuya Taki while he fights Hongo. At first Ikadevil has the upper hand, but with guidance from Tobei, Rider #1 manages to overpower Ikadevil and weaken him with a Rider Chop aimed at his weak point near the neck before finishing him off with his Rider Tailspin Shoot.

Along with Colonel Zol, Ambassador Hell, and General Black. He was resurrected by Doktor G to initiate Operation: Japan Annihilation using a new toxic gas called Girard Gamma. His assignment is Osaka. When Ambassador Hell captured by V3, he is agree to execute him alongside V3 until Great Leader interference stating they cannot afford to lose even Ambassador Hell when carried out their mission and let V3 go as he pleases. He died with the other revived commanders when Destron's base accidentally self destructed.

Due to a change in history caused by Ankh leaving a O Medal behind in 1971, Shocker created the Shocker Greeed. The Double Riders learn about Shocker's plan and attempt to replace the medal with a tracker device to find their headquarters. However, they had merely secured another fake medal and were ambushed when attacking Shocker, facing a large army of resurrected monsters, which included the recently defeated Ikadevil and Garagaranda. These troops eventually manage to overwhelm and capture the Riders, while their allies escaped. In the present, Ikadevil continued as a Shocker member even as it expanded to include members from other groups that would have been separate organizations in the original timeline, alongside making a huge alliance to lead under its banner the organizations that did appear. When the riders returned as people's belief in justice partially restored the timeline, Ikadevil along with Ganikomol and Garagaranda was destroyed by Kamen Rider Den-O Climax Form Boistous Slash and Kamen Rider New Den-O Counter Slash.