Kai Hiwatari,his bit beast is Dranzer Kai appears in the end of the very first episode of the show; at the time Kai is the team captain of the Blade Sharks (a group of beybladers that terrorize others who play the game by defeating them and stealing their blades), as well as the Beyblade world champion. Tyson Granger, the main protagonist of Beyblade and Kai meet after one of Kai's 'underlings', Carlos, loses to him. Kai defeats Tyson as easily as Tyson did Carlos, though he does not use his bit beast for this victory. Later on, Kai kidnaps Tyson's genius friend Kenny, and is challenged by Tyson for his freedom. The fierce battle ends in a tie thanks to Tyson's new bit-beast, Dragoon. Kai releases Kenny anyway and leaves. No further confrontation occurs between Kai and Tyson until the Regional Tournament, in which Kai participates and defeats many of Tyson's friends on the way to the finals, including Max Tate.

In the finals, Kai and Tyson battle a close match but Tyson wins. After the battle the director of the BBA, Mr. Dickenson, offers Kai a position as team captain of the Bladebreakers, due to Kai's position as world champion and his great experience in the sport. Though Kai is unconvinced, his pride pushes him into accepting leadership. The team goes on to win the Asian and American tournaments (with little participation of Kai); they also defeat the top European team: The Majestics. At this match, Kai plays a significant role, defeating Johnny. At the World Championship, after visiting Balkov Abbey, Kai begins acting strangely. In a bold step, he leaves the Bladebreakers and joins with his grandfather Voltaire, and his team, the Demolition Boys. Here, Kai reunites with a powerful bit beast he had become enraptured with as a child; the seemingly perfect Black Dranzer. With this new bit beast Kai is able to get the Demolition Boys all the way to the finals. Before these, Kai issues a challenge to his former team, even sending a helicopter to escort them to the frozen Lake Baikal. There, Kai battles Tyson, Ray, and Kenny, overwhelming them all with his power. Just when Tyson's Dragoon blade seems about to be demolished, Max arrives on the scene with his brand new, much stronger Draciel blade. Tyson takes the opportunity to launch Kai's abandoned Dranzer blade, and Dranzer's anger, as well as the combined determination of Ray, Tyson and Max, pushes Kai into realizing the true power of friendship. The ice begins to crack, but Kai, frozen in realization of his pride, refuses to move. It is only after a few words of support from his team that he sheds a tear and allows them to pull him back onto solid ground. After this near-death experience Kai acknowledges his role as leader of a great team and rejoins the Bladebreakers for the championships After the events of Season 1, Kai decides to retire from beyblading to attend the Whitney Prep School. During his time there, though, he is attacked by a mysterious blader, Dunga, and saves a fellow classmate and his admirer, Wyatt, in the process. The intense fight Kai has with this blader rekindles his interest in beyblading and inspires him to return to the Bladebreakers. To his surprise, all of his former team-mates have been attacked by mysterious bladers too. These turn out to be the Saint Shields, a group that later reveal their wish to capture the four sacred bit-beasts. Later, Kai and the team encounter strange cybernetic bit beasts that are exact copies of their own bit beasts. One of those to wield a prototype of these beasts is Wyatt, who challenges Kai, but is instead fought by Dunga. Wyatt loses and falls into madness and later dies (though this is not revealed in the English dub). Kai blames himself for Wyatt's suffering, since he had previously refused to acknowledge him as worthwhile competition, driving the boy to seek other ways of gaining Kai's attention.

Later, the Bladebreakers finally fight a team that can survive the awesome power of the cyber bit-beasts: The Psykicks. They are former friends, but their minds are taken over by their bit-beasts. Kai manages to break the bit-beast's hold over Goki, the user of Cyber Dranzer, despite having hallucinations of battling Wyatt. With Team Psykick freed from the hold of the cyber bit-beasts through the efforts of the Bladebreakers, the friendships are restored.

At the start of this season, Kai follows Ray and Max's lead and, in an effort to prove to himself that he is a better blader than Tyson, leaves the team. He joins the newly re-formed team Neoborg (Blitzkrieg Boys in English dub), which is now out of Boris' control. Kai and Tala team up in this double-elimination, round robin, tag-team format tournament and make it to the finals with only one loss out of six matches. In the finals Tyson and Kai face off after Daichi ties with Tala. The battle is more fierce than any of their past fights against each other. It is so extreme that the arena starts to crumble. Mr. Dickenson asks that the two call it a tie and share the title, but this does not go over well with many, Kai especially. "No way! You can't do that to me! Are you telling me that this tournament has been nothing but a complete joke? That everything that we did doesn't count because you decide we get punished for working hard?" he shouts at Mr. Dickenson upon the announcement of the decision. Ray votes for the match to continue, quickly joined by Max and many fans and bladers. After some coaxing the two are allowed to finish their battle. Kai and Tyson match each other blow for blow, eventually releasing powerful finishing attacks. They stare each other down afterwards, but Kai collapses, losing the battle.

Kai is missing for some time and does not reappear again until he shows up to enter the qualifier for the BEGA Justice 5 Team, meaning that he won't battle with Tyson and the others in order to finish the BEGA League. He stays in this tournament until the final round where he goes up against the top class blader Brooklyn. Kai does his best but is greatly overpowered by Brooklyn's skill and dark bit beast Zeus. Kai goes into hiding once again, only to emerge as the G-Revolutions' fifth member. He battles Brooklyn again using his upgraded Dranzer MS blade. It is a hard and torturing battle for Kai, but in the end he emerges victorious. The victory does not come without a heavy price, however. Kai only survives to make his final attack through his bit beast. His beloved friend, Dranzer, appears to sacrifice its life to protect him, as shown after Kai's battle with Brooklyn, when the Dranzer MS suddenly shatters with the cry of a Phoenix.

This shatters Kai's morale, although the effect is lessened by Dranzer's reappearance in the last episode, engaging Dragoon in battle. Dranzer's reappearance could be explained by the fact that Dranzer is a phoenix and that phoenixes are revived from their ashes. This does however follow the trend to have bit beasts play a more incidental role in this series. After Tyson defeats Brooklyn, everything returns to normal, almost coming full circle, with Tyson owing Kai a rematch from the tournament. However in the original Japanese version it was heavily implied that Kai actually dies (Kai himself only says one line of dialogue when he is in the corridor after the match with Brooklyn and Dranzer does not cry out), backed up by Tyson's reaction to his "death" in the following episodes, but does not explain how Kai came back in the final episode.

Beyblades and Attacks

Dranzer S- Fire Arrow,Spiral Survivor Dranzer F- Flame Saber Dranzer V- Volcano Emission Dranzer V2- Volcano Exellent Emission Dranzer G- Blazing Gig,Blazing Gig Tempest Dranzer GT-Flame Gigs Turbo,Blazing Gig Tempest,Blazing Gig Reverse Attack Dranzer MS- Spiral Fireball