Kai is a serious person and doesn't like to joke around like other kids his age. He doesn't talk much or to anyone. When cardfighting, he is shown to be more serious and confident on winning the game without any need of support. Despite his selective mute personality, he has a best friend in Taishi Miwa.
Toshiki Kai main deck focus is the Kagerō clan deck. His trump card is Dragonic Overlord. His strongest and most commonly used cards are normally Flame Dragons.

In season 2 of the 2011 series, Kai's main deck focus is the Narukami clan deck. Kai stays with this clan in Season 3, although he hasn't given up on his Kagero deck. After seeing how far Aichi has come, Kai now doubts his own strength in comparison and seems to be striving to prove that he's able to keep up.
~!Kai's concerns worsen during the VF High School Tournament and he fears he's falling behind. Previews have him affiliated with the new Link Joker clan.!~

The protagonist of this story, Sendo Aichi, is a timid boy in his third year of middle school. He had been living his life looking backward rather than forward, trying not to stand out. However, he had one thing that kept him going - the "Blaster Blade," a card from a card game that was given to him when he was little. That card is the reason why he begins to engage in Card Fights, something that changes his life drastically. 
The name of the card game is "Vanguard." The game takes place in a different planet called "Cray," and due to a never before seen play system, it becomes popular throughout the world. 
Aichi, immediately attracted by Vanguard, meets friends such as Tokura Misaki and Katsuragi Kamui, along with other rivals. Through friendly rivalry with them, Aichi begins to enjoy a fulfilling life. Aichi, however, has a goal: to once again battle with a Vanguard Fighter by the name of Kai Toshiki. Kai Toshiki is an aloof and cold-hearted high schooler who has outstanding abilities in the world of Vanguard. He is also the reason why Aichi started playing the game. For him, Toshiki is the person who saved him from his boring life and introduced him to Vanguard. In order to get better at Vanguard, Aichi puts his soul into it every day. He wishes that someday, he'll be able to battle Toshiki and have him recognize his worth. 
(Source: Crunchyroll)

He's Korean.  He played dubbing voices for   Shiro from "Fate/Stay Night",  Sasuke Uchiha from "Naruto",  and etcetera.    He played the voices of characters in video games.  One of the famous roles he played was the protagonist called Calintz in the video game called Magna Carta  

__[Twitter](https://twitter.com/5takuya5)__

Born in Rome. Has two brothers, Francesco Vivio and [Paolo Vivio](https://anilist.co/staff/115558)

A few months have passed since the VF Circuit, and Aichi is now in High School. However Aichi is in a different high school than most of his friends, a high school where the instructors focus on looking towards the future. One day Aichi admits he thinks Cardfight can be a future people can believe in, but in order to prove it Aichi must use his new deck, a deck in which Royal Paladins and Gold Paladins are combined as one force. Slowly but surely Aichi must gain friends through Cardfighting and help his new team win the newly formed high school cardfighting championships. 
(Source: Anime News Network)

Aichi and his friends have won the National Tournament and decide to go their own ways until a mysterious boy named Takuto Tatsunagi appears. He reveals that the Royal Paladins, Shadow Paladins, and Kagero leaders have been captured, and the only way to free Cray is for the Vanguard fighters to use a new power- Limit Break. Because the Royal Paladins lose the ability to fight, Aichi's deck is changed to be a Gold Paladin deck. Aichi and his friends must now win the Vanguard VF Circuit if they are to learn more about the occurrences on Cray and free their old friends. 
(Source: Anime News Network)

Several days after the mortal battle against Link Joker which embroils the whole world, the world has returned to peace. 
But Kai Toshiki faces a surprising situation. Sendou Aichi, the hero who saved the world from the invasion of Link Joker, has suddenly disappeared. In addition, everyone's memory about Aichi is lost...Almost all hints have been lost, and Kai starts to search Aichi with "Blaster Blade" and the deck of Royal Paladin, the only existing hint and the proof of their bonds. 
Kai is approached by fighters who call themselves "Quatre Knights". The four---Gaillard, Neve, Ratie and Sarah---are fighters with world-class power in vanguard fights. They control mysterious power and urge Kai to give up searching Aichi. What is their purpose...!? And what is their relationship with Aichi...!? 
Kai, with the new power "Legion" in his hand, fights to take Aichi back. Now, the war has begun! 
 
(Source: Cardfight!! Vanguard Wikia)

The main protagonist Sendou Aichi, is a timid and mundane third-year middle school boy. The thing that supported Aichi's heart, was the "Blaster Blade" card that he received as a child. It's an important rare card from "Vanguard", a card game with the imaginary world of "Planet Cray" as its stage. From the day he reunited with the person who gave him that card "Toshiki Kai", Aichi's everyday life began to change. (Source: Crunchyroll)

Team TRY3: Chrono, Shion, and Tokoha, managed to win the championship of Generation Quest. In the mean time, however, Ryuzu Myōjin has a secret plan: summoning Zodiac Time Beasts of Gear Chronicle clan to Earth. Chrono and Kouji want to stop Ryuzu, but they are confronted by a mysterious group of cardfighters known as "Company" who share Ryuzu's ideology. (Source: Anime News Network)

After the events of Link Joker-hen, Takuto Tatsunagi announced an invite-only tournament in a dream, and invited both Aichi and Kai to take part in "Messiah Scramble". The prize being the card named "Messiah", the name of a saviour that was heard in a dream. At the same time, there were many incidents of units disappearing from Vanguard cards throughout the world. Aichi and Kai team up to a confront an enemy that threatens the peace they've just regained. 
 
The movie is a prequel to Legion, leading up to Aichi's disappearance.

Diffriders referred to as “Apostles” from Planet Cray descend upon Earth. “Dragon Deity of Destruction, Gyze”, who destroys everything. The “Apostles” who envision the revival of Gyze, manipulate the power of the six “Zeroth Dragons” and invade the Earth. 

(Source: Anime News Network)

Team TRY3 members Chrono Shindou, Shion Kiba and Tokoha Anjou move forward to their respective high schools. Each member forms their own team in a bid to decide their own future. The three protagonists are set to clash as rivals in the upcoming large-scale tournament titled U20 Championship. (Source: Anime News Network)

A major event known as "G Quest" is to be organized by the Federation of International Vanguard Associations (FIVA) this autumn. Those who conquer six Branch Quests will be honored the title "Generation Master" as well as the chance to become a Clan Leader. While members of TRY3 are all excited by new goals ahead, a massive conspiracy that would lead to the destruction of Vanguard has been secretly set in motion. 

(Source: Anime News Network)

The history of -IF- world has been distorted and cardfights do not exist. Ibuki and Suiko get involved with Emi and Shuka.
 
A journey to regain the true history by four people begins—! (Source: Cardfight!! Vanguard Wiki)

Aichi Sendou and the Miyaji Cardfight Club aim the win the national championship, but problems arise after the timeline has been rewritten and taken Kourin off the team. Now Aichi and company must find a way to get back to 5 members to compete while the Student Council tries to shut them down. Meanwhile Kai battles his own demons as he tries to figure out how to reconnect with his cards, and Kouji Ibuki must decide whether he wants to give up the game or find a new way to play that doesn't involve deleting others. (Source: Anime News Network)