Isaka

Isaka, aka the Peacock Undead, is the Category Jack of Diamonds Undead and a major antagonist in Kamen Rider Blade. He is the first Category Jack Undead to appear.

Kamen Rider Blade
Isaka is the one who created the Rider System 3 which would allow someone to transform into Kamen Rider Leangle. However, Isaka modified the belt so that it would require the Ace card containing the Spider Undead, causing its user to be possessed by the Category Ace Undead. He also tricked Kamen Rider Garren into working for him and got him to eat the Schuld Ketsner seaweed, telling him that the seaweed would eliminate his fear when in fact it would only increase his aggression. Eventually, Garren's girlfriend Sayoko took notice of her lover's addiction and increased rage, prompting Isaka to kill her to prevent her from helping him. This caused Garren to realize the truth and turn against Isaka, leading to Isaka meeting his end when he was defeated and sealed by a vengeful Garren.

Kamen Rider Blade: Missing Ace
Isaka appears in a preview where he goes after Natsumi Miwa and Shin Magakibefore only to be defeated offscreen by Kamen Rider Glaive.

Kamen Rider Blade (video game)
The Peacock Undead is one of the Undead who appears in the Kamen Rider Blade video game.