- Died: 1862/8/24
Sasu Iori was a prominent Tsushima han official in the 1840s-1860s, and the domain's chief councilor in and around 1859-1862. He is known most, perhaps, for his efforts to petition the Tokugawa shogunate to take over responsibility for the flailing and endangered island domain, transferring the Sô clan to another fief.
In 1846, along with Yoshikawa Saemon, Sasu submitted a memorial to rôjû Abe Masahiro arguing for Tsushima's importance as a "bulwark," a physical barrier protecting the realm from outside invasion, and petitioning for additional fief land for the Sô, in order to help fund the expansion of the domain's coastal defenses. This perhaps marks the first significant instance of Tsushima officials describing the importance of their domain to the realm in strictly military terms; previous memorials had focused upon the domain's importance in trade, foreign relations, and intelligence. This request was rejected, though others in succeeding years earned additional financial support for the domain.
The late 1840s into the 1850s saw a dramatic increase in the number of Western ships seen off the coasts of Tsushima, and the number calling at the island. Fearing further Western incursions, and the domain's inability to deal with them, Sasu sent a memorial to the shogunate in 1859 suggesting something he, his fellow advisors, and their lord had been discussing for some time. They asked the shogunate to take over responsibility for the island and its defenses, and to transfer the Sô to another domain, while retaining the Sô as intermediaries in relations with Joseon Korea. Shogunate officials began to discuss the issue, but the whole thing was dropped when Tairô Ii Naosuke was suddenly assassinated in 1860.
Sasu raised the issue again following the Posadnik incident in 1861, when a Russian sea captain, intent on establishing a base on the island, sat anchored at Tsushima for over six months, refusing to leave despite requests, negotiations, and pressure from both Tsushima and shogunate officials, and ships & officers of the British Royal Navy. Nonoyama Kanehiro, magistrate for foreign affairs dispatched to look into the issue, however, determined that taking over Tsushima would be too expensive and difficult for the shogunate, and so Sasu's petition was rejected again in 1862.
Despite his prominent role in making these proposals, Sasu in fact stood on shaky political ground throughout these events, and had many enemies within the domain court as the result of succession disputes. Different factions at court had supported different consorts of the daimyô Sô Yoshiyori since the 1840s, each of whom wanted to have her son be named heir. Sons of each consort were, in fact, named heir in turn, but both died while still young. When the designated heir, a son of the consort Midori, died in 1859, Sasu supported her other son being named heir, but was opposed by others at court, who supported instead Yoshinojô, a son of the daimyô by his samurai wife. The latter faction eventually, in 1860/10, organized a band of several hundred armed men who attacked the daimyô's palace, freeing a handful of men imprisoned by Sasu, and forcing the daimyô to name Yoshinojô and not Midori's son, his heir. Sasu continued to serve as chief councilor, retaining his ranks, titles, and post after this, but with the opposing faction having gained considerable successes, was in a decidedly less secure or powerful position from then on.
Some of the freed political prisoners, along with other members of the opposing faction, launched an attack on the Tsushima han residence in Edo on 1862/8/24, where, after a heated verbal exchange, they killed Sasu, declaring him a traitor to the domain for having tried to dispossess the Sô clan of their traditional lands.
In the aftermath of Sasu's death, the newly ascendant faction formed an alliance between Tsushima and Chôshû domain; with the help of prominent Chôshû retainer Kido Takayoshi, they then convinced Yoshiyori to step down in 1862/12. Yoshinojô, taking the name Sô Yoshiakira, then became daimyô.
- Robert Hellyer, Defining Engagement, Harvard University Press (2009), 168-169, 208-210, 216-218.