The Copper Coin Society Affair

Edo in the sixth year of Tenmei, with Tanuma Tonomo-no-kami at the head of the rōjū and the blossom out at Ueno. In a teahouse by the Ryōgoku esplanade, Oiro of the Ginkgo Teahouse tells the young samurai Shirahata Yuminosuke that she is leaving him: she has been bought as a concubine, and the man buying her is Tanuma — the same minister who had Yuminosuke's father stripped of his post as Keeper of the Keys.

Then Yuminosuke sees a townsman at a teahouse shifting ten cups and a single pot into rows, squares and arcs, and hears an old white-haired warrior murmur: the teacup array of the Copper Coin Society. Following him leads to the Ōoka mansion at Yanaka, to Yuminosuke's uncle Magaribuchi Kai-no-kami, magistrate of the North, and to the news that the Shōgun Ieharu has been carried out of Chiyoda Castle by a woman in a furisode and a shimada knot, and has not been seen since. A dagger with the Society's name cut into the hilt had already been thrown at his palanquin on the Hongō road.

The novella is built out of ciphers and set pieces: four chains that fly out of four pillars and pin an intruder to the tatami; a house in Hanakawado where the six great thieves of the Tenmei era give their names at the wicket one by one; a beggar under Ryōgoku Bridge, Katō Sadenji, who reads pebbles and the Book of Changes; a chronicle tracing the Society back to the burning of Shōrinji and five surviving monks; a catechism of passwords about jewels, tigers and a bridge; the greatest manhunt since Keian; and a gate that opens on sixteen men hanged with plaited-hair cords. History closes it — Ieharu dead soon after, Tanuma pared down to ten thousand koku, Matsudaira Etchū-no-kami in his place — and Yuminosuke and Oiro close it too, in a four-and-a-half-mat room with the goldfish-seller calling outside.