Tokugawa Yoshinobu

A playboy known around town by the name Keiki. He's actually head of the Hitotsubashi family, and a contender to become the next Shogun. He has plenty of money and power, yet he seems unhappy somehow, and dislikes anything transient or impermanent. He shows an interest in the protagonist as she works at Shiki, and the two of them gradually become closer.