Theres not a lot of information about Kai, only the very well known things. His personality is typical
cold
emotionless
calm
strong.
He doesn't like bein told what to do and has betrayed the bladebreakers numerous times.

Mood:  don't ask
name: Kai Hiwatari
Age: 13/14

I LOVE KAI!

Kai's Bitbeast, called Dranzer, is best known for its Fire Arrow attack, but Dranzer also gives Kai's blade a defensive move called Spiral Survivor, which can give it an unusual spin that makes it a difficult target to attack. Kai normally plays aggressively, like Tyson, but he also has the wisdom of experience, so he also knows how to employ strategy.

Kai knows very little about his childhood, and before he became captain of the Bladebreakers he ran his own gang of bladers called the Blade Sharks. It will be a shock when he learns the truth about his early life late in the series.

Kai is an anti-social boy who has had a very hard childhood. He is captain of the Bladebreakers, and was forced into beyblading by his grandpa, the source of all his misery. Kai is a realist and the best at everything he does. He seems to hate people, but who can blame him; compared to him most of them are intolerable idiots.

In G-Revolution, Kai is in the Demolition boys for some time. And apparently, Kai was also a member of BEGA for a short time.

Kai is best friends with Tyson, but they are also rivals. No one can beat Kai except Tyson.