Arriving in the World of Blade, Tsukasa takes the role a 2 of Spades Ace Chief Waiter, working at BOARD Corporation, a mega corporation that assigned hired Kamen Riders to battle the Undead under and immoral ranking system. However when an Elephant Undead shows up, he witness Sakuya Hishigata (Kamen Rider Garren) battling it before Kazuma Kendata (Kamen Rider Blade) shows up. When the Capricorn Undead shows up, Tsukasa joins in the fight as Kamen Rider Decade and defeats Elephant Undead using Ryuki's powers. Meanwhile, Natsumi and Yusuke meets Hajime Shiko, BOARD's president, to negotiate with him regarding saving Blade's world from being destroyed. However Hajime refused to help them since they don't have the money for their services.
Just them, Kazuma, Sakuya, Mutsuki and Tsukasa are summoned into the Hajime's office, much to Natsumi and Yusuke's surprise upon seeing Tsukasa. Kazuma was demoted from Ace of Spades to 7 of Spades for violating the rules for protecting Mutsuki(Kamen Rider Leangle) from Capricorn Undead and letting the Undead escape. On the other hand, Tsukasa was promoted to King of Spaces, much to his delight, while Mutsuki's promoted to Ace of Clubs. Despite Kazuma's pleading, Hajime ignores it and reassign him to work under Tsukasa in the cafeteria. Unfortunately, Kazuma was demoted to 2 of Spades for his poor performance in the cafeteria and was asked to hand over his Blay Bucklet. Unfortunately, after hearing Hajime's excuse of his demotion, Kazuma refuses to hand it over and run off.
Soon, Tsukasa catches him in an open field, trying to convince him to the right thing since he's his superior. Suddenly, Kamata arrives threatening Kazuma to hand over his Buckle before transforming into Paradoxa Undead. While Decade battles Paradoxa Undead and Capricorn Undead (who joins in later), Sakuya and Mutsuki arrives to convince Kazuma to surrender his Blay Buckle so he won't get fired. Unfortunately he refuses and transform to Blade while battling both Kamen Rider Garren and Kamen Rider Leangle. After Decade defeats Capricorn Undead, suddenly everyone's fight was interrupted by the appearance of Kamen Rider Chalice, who manages to take out all of the riders and steal Kazuma' Blay Buckle. After Decade stands up, both Chalice and Decade face each other one-on-one.
- Alternate Universe: The World of Blade is one to the setting of Kamen Rider Blade.
- Instant Costume Change: Upon arriving in the World of Blade, Tsukasa becomes an employee of BOARD.
- Monster of the Fortnight: The Paradoxa Undead.
- Two-Part Episode: Part 1 of the World of Blade arc.
