Kai Hiwatari  

, 火渡 カイ

In the series, Kai is portrayed as a "bad boy" character. At first, he and Takao dislike each other intensely when they meet. Kai holds a grudge against Takao because of their initial confrontation where Kai loses the battle in front of him, and also due to his perception that Takao is picky, annoying, and immature. On the other hand, Takao does not harbor any ill feelings towards Kai as he only wishes to be friends with him. However, this proves challenging because of Kai's aloof attitude towards beyblading and life in general. Over time, Kai evolves into a BladeBreaker, accepting Rei, Max, Takao, and Kyouju as his teammates. As a natural leader, he leads the Blade Sharks (which he later leaves), BladeBreakers, Demolition Boys (Neo-borg). Despite betraying his friends multiple times, it appears that power is what motivates him most. Later on, his reasons shift to wanting to defeat Takao specifically. Kai's difficult childhood and lack of social interaction have made him cold and indifferent towards others. However, he gradually opens up as he forms a close bond with Takao. While he develops friendships with other team members, it is clear that Takao holds a special place in his heart.