The Sankin Kotai was a system created by Tokugawa Iemitsu in order to ensure that the daimyo under his rule would have a degree of cohesion. It was also a major pain in the neck for those daimyos, who had to plan for a major pilgrimage to Edo every other year! Moving that kind of distance every few months in the 17th century wasn't easy!
He's reading a book out loud 
so our lord will stay awake,
Lo mantienen despierto para ser menos
susceptible a intentos de asesinato.
Ele tá lendo um livro em voz alta
pro nosso senhor ficar acordado,