Tokugawa clan warrior, a retainer to the Tokugawa family and advisor to Ieyasu. He's served the Tokugawa clan since he was a child and, being an old friend to Ieyasu, he's one of the very few people who can address him simply as "Ieyasu" instead of using an honorific title. Sakai has an unusual kind of rivalry with Tadakatsu and harbours an unspoken dissatisfaction at Tadakatsu being valued more than he is. His motto is "Believe!"