Toshiki Kai is one of main characters in the anime and manga. During Season 4, he becomes the main protagonist after Aichi's disappearance. He is also the main protagonist of Neon Messiah, along with Aichi. He is a very serious character. It is known from the end of episode 1 that he had previously met Aichi and gave him the card Blaster Blade, which later becomes the heart of Aichi's Royal Paladin deck. His Vanguard Circle color is red.