A document written by a 16th-century warlord and first leader of the Sendai domain, Date Masamune, was recently analyzed and deciphered at a museum in Himeji, Hyogo Prefecture. Yamagata University Professor Emeritus Kenji Matsuo believes that the letter was sent to the hatamoto, or high-ranking samurai, Tsumaki Yoritoshi in 1635, early in the Edo era. The document, translated into modern Japanese, says this: “On the morning of March 16, Hosokawa Tadatoshi (who was also a daimyo) will go to the residence of Date Masamune in Edo. If you don’t have any prior commitments, would you like to join us?”
In an article in the Japanese newspaper The Mainichi, Professor Matsuo explains that “Tsumaki was not a daimyo but a hatamoto with a fief of only 7,500 koku of rice, while Masamune was a daimyo with a fief of 620,000 koku. Considering that Hosokawa was also the first lord of the Kumamoto domain with a fiefdom of 540,000 koku in Higo Province, this historical source indicates that Masamune had established relationships with them regardless of the difference in their social position based on their last names.”The 35 centimeter by 43 centimeter letter was donated to the museum in 2019 by an individual. Due to severe damage, some parts were unreadable, but Matsuo and others knowledgeable in medieval Japanese history were able to decipher the message.