Above the racetrack, past forested slopes carved by stonewalled passages that encircled and ascended the hill, a compound stood isolated from the estates that housed the top officials of the Tokugawa regime. High walls topped with metal spikes protected the compound, whose tiled roofs rose amid pine trees. Samurai officials, wearing formal silk robes and the two swords, shaved crowns, and topknots of their class, queued up outside. Guards escorted them in the double gate, through the courtyard, into the mansion that rambled in a labyrinth of wings connected by covered corridors. They gathered in an anteroom, waiting to see Chamberlain Sano Ichirō, the shogun’s second-in-command and chief administrator of the bakufu, the military government that ruled Japan. They passed the time with political gossip, their voices a constant, rising buzz. In nearby rooms whirled a storm of activity: The chamberlain’s aides conferred; clerks recorded business transacted by the regime, collated and filed reports; messengers rushed about.

Closeted in his private inner office, Chamberlain Sano sat with General Isogai, supreme commander of the army, who’d come to brief him on military affairs. Around them, colored maps of Japan hung on walls made of thick wooden panels that muted the noise outside. Shelves and fireproof iron chests held ledgers. The open window gave a view of the garden, where sand raked in parallel lines around mossy boulders shone brilliant white in the afternoon sun.