|“||I am...the one who will become the destroyer of worlds.||”|
A mysterious young teen suffering from amnesia, he has no memory of his past, sans being told by a man named Narutaki that he will become the "destroyer of worlds." He is also the holder of the Sacred Gear, Boosted Gear, one of the 13 Longinus, which are said to kill both Gods and Maous. As a result, he is a dangerous opponent.
Furthermore, Issei is one of the Kamen Riders of the New Era, serving as the successor to Tsukasa Kadoya. As such, he is the new Kamen Rider Decade.
Issei's appearance is slightly different from his cannon counterpart, in that his brown hair is matted down, and his eyes are a significantly lighter shade. He also likes to wear a dark red turtleneck sweater with a black jacket, as well as dark pants.
Issei is different from his counterpart, in that he is more cynical and callous. He also lacks any perverted traits, but he does admit that he has some appreciation for a woman's breasts. Because he has no past to speak of, he tends to shy around minor details, and goes along with the flow, often creating the illusion that he is a jokester or simply a fool. In fact, he only acts like a pervert simply because it was how the student body saw him as, and saw no reason to rebuke them either. This often causes confusion when people see how he really is.
As Decade, Issei comes off as cocky and slightly taunting, but never underestimates his opponent. He is calm, calculating, and very resourceful, and can be slightly intimidating due to his abilities.
Issei's past is rather ambiguous, due to having lost his memories at some point in time. The only thing he remembers is meeting a man named Narutaki, who gave him his Decadriver and Ride Booker, telling him that he will become the Destroyer of Worlds. He also tells him that one day, he will be asked how the world looks through his eyes, and that when that times, he must give them an answer.
His life in Kuoh is the same as his cannonical counterpart, even having the same reputation, though this was later shown to be a ruse by Issei, who was simply going along with the idea of him being a pervert. However, he reveals his true self during the Rating Game, revealing himself to be Kamen Rider Decade, and announcing that he will become the Destroyer of Worlds.
- Because he lacks a last name, and due to the lack of information the author provides, it is unsure of this Issei has any connection to the Hyoudou Family. It can be inferred that he does, given that he calls Irina by name, despite having no memories of her.
- It is implied that, like in the show Kamen Rider Decade's story element, Issei is from an alternate world, as he does not have any memories, much like KR Decade's own protagonist, Tsukasa Kadoya.