|“||I have understood your Vanguard.||”|
—Kazumi Onimaru's catchphrase
He has long, very light blond or even white hair that's tied in a pony tail and yellow eyes. He wears a black suit over a red shirt.
Under Shirauni's control, he has a gentle but sinister tone. Eager for combat, he has shown to be both meticulous and ruthless during a fight. Shiranui doubts humans should be the ones who guide the fate of Planet Cray, and looks down on weak cardfighters he defeats. This changed, however, during the climax fight of the Under20, where Chrono Shindou show Shiranui the truth of Vanguard, after having been mislead by Evil God Bishop, Gastille all this time.
Once the Diffride contract is broken, Kazumi does not hold any ill will against Shiranui. Instead, he feels remorse and feels that he was too weak to help out Shiranui. Kazumi's true personality is shown, and is similar to the persona used by Shiranui when he first encountered Chrono.
In NX Episode 1, he enters Card Capital 2, looking for Chrono Shindou. He eyes Chrono, making sure that it is him, and asks Chrono to a cardfight. Multiple times throughout the fight, Kazumi says odd things that make Chrono act nervous and be suspicious of him. Kazumi quickly defeats Chrono, who was caught off guard by Kazumi's hand-destruction tactics, winning by using Rikudo Stealth Rogue, Atagolord's skill and by drive checking a critical trigger while Chrono was at three damage. Before the fight is over, he asks if Chrono has any plans of entering a tournament. After the fight, he leaves the shop and tells Chrono his name. Chrono searches him up on the shop's computer and finds that Kazumi is the previous champion of the Under 20 Championship. Chrono walks up to a poster on the shop advertising the tournament, and becomes excited to enter.
He clears the first stage of the U20 alongside his team on the first day with ease, but remains on site observing the rest of the cardfighters. When Noa Hoshizaki follows a voice he heard to an enigmatic, red coloured portal, a system that was set up by Saori Fuchidaka to temporarily sabotage the power throughout the U20's facilities is activated, and Kazumi immediately moves to find out who touched the portal. Along the way however, he is spotted by Chrono, and the two are then found by Ibuki, who was already suspicious of Kazumi. Kazumi and Ibuki face off, bringing up their ideals for a future world, however they discontinue the match when the power returns to the U20. Soari gives Kazumi a second opportunity to reach the portal by hacking into the particular security cameras that were nearby. Kazumi enters the portal, and immediately performs a "Different World Ride" on Noa, wherein Star-vader, Chaos Breaker Dragon possesses the "vessel of his other self" (Noa).
It is later revealed by Nome Tatsunagi, that Kazumi's Different World Ride with Stealth Dragon, Shiranui was not something he agreed to, and Shiranui has found a way to forcibly Diffride. As such this means that Shiranui is in complete control of Kazumi.
It is revealed later on that in his first meeting with Miguel Torres, Miguel-Antero claimed that humans had a "hidden potential". Kazumi-Shiranui is intrigued, and begins to wonder if it exists.
He grows progressively more obsessive about this, and slightly maniacal, when his expectations are not met by the various contenders in the U20's second stage. After beating Kumi Okazaki and demeaning her fighting-style, an enraged Satoru Enishi challenges him. During the fight, Satoru pushes Kazumi-Shiranui further than he expected, with Kazumi-Shiranui wondering what power is Satoru emanating, which appears to satisfy the latter for the time being.
When using his Domination deck, he also appears to be fighting with a more savage nature, as shown with his eyes widening in pure satisfaction whenever he dominates an opponent's unit, as opposed to his calm, calculated disposition when utilizing Afterimage.
It is shown during his fight with Kazuma Shouji that Shiranui has access to Kazumi's memories at will, as he quickly figures out who Kazuma is, and becomes eager to test his strength, hoping for a similar tenacity shown by Satoru.
Ultimately, Kazumi-Shiranui is left disappointed with Kazuma's efforts, and potentially even disgusted, viewing the latter as weak and remarking that he "now understands why" Kazuma and his mother were outcast from the Onimarus.
After Kazumi-Shiranui beats Kazuma, he faced Chrono in a cardfight where he reveals his intention of destroying Vanguard to shatter the bond between Earth and Cray.
Kazumi uses a Nubatama deck, with Stealth Dragon, Shiranui as his ace. It focuses on the Afterimage skill, allowing him to return his units to his hand at the end of his turn and potentially re-use on-call skills. Like all Nubatama decks, its win condition is to limit the opponent's defensive options with hand destruction. To make this strategy even more devastating he uses Rikudo Stealth Rogue, Atagolord, a G Unit who gains critical when the opponent has 3 or less cards in hand.
For the U20 second stage his deck changes. His new deck focus more on units with the new Dominate ability, which forces his opponents rear-guards for one turn to attack their owner's vanguard and forcing his opponents to call units from his/her drop zone to dominate, while gaining benefits from dominating units. His deck's new ace is Demon Stealth Dragon, Shiranui "Oboro", while his new G unit Enma Stealth Rogue, Mujinlord can dominate multiple rear-guards in one turn. He then adds a new card Evil-eye Hades Emperor, Shiranui "Mukuro", which allows him to dominate the opponents Vanguard. Once the Diffride contract is broken, Kazumi continues to use this Domination-based deck, instead of the Afterimage-based deck he used when he was younger, as a sign of respect to Shiranui.
- May those evil eyes foresee all the consequences. Ride! Stealth Dragon, Shiranui!
- Overcome truth, Reveal truth! Stride Generation! Enma Stealth Rouge, Mujinlord!
|Record (Season 8)|
|Chrono Shindou||Turn 1||Win|
|Tokoha Anjou||Turn 15||Win|
|Shion Kiba||Turn 15||Win|
|Sugiru Kariya||Turn 17||Win|
|Kouji Ibuki||Turn 22||Unfinished|
|Am Chouno||Turn 32||Win|
|Luna Yumizuki||Turn 32||Win|
|Kumi Okazaki||Turn 32||Win|
|Satoru Enishi||Turn 32||Win|
|Kazuma Shouji||Turn 34||Win|
|Chrono Shindou||Turn 35||Win|
|Shion Kiba||Turn 42||Win|
|Kazuma Shouji||Turn 49||Win|
|Chrono Shindou||Turns 50 to 52||Lose|
- Across all seasons of Vanguard (both original and G), he is the earliest introduced antagonist, appearing in the first episode of his debut season (NEXT).
- He is known to have bad luck at rock paper scissors.