Sayaka (沙也可)
Sayaka (?) (沙也可, also written as 沙也加) (1571? - 1643?) (Korean name is Kim Chung-seon) was a person who allegedly went to Korea under the command of Kiyomasa KATO during the Bunroku-Keicho War (Jinshin waran in Korean), but surrendered to join the Korean army and fought off the Japanese army. Although he is seen as a hero in the Korean Peninsula, there are many question marks regarding the reality of his achievements.
Tradition
It is said that Kim Chung-seon left a record called '慕夏堂文集',but because the description of 慕夏堂文集 has pronounced the Korean sense of value (such as the attitude toward Ming) and Confucian quality, it is hard to believe that it was written by a busho (Japanese military commander) who was born and raised in Japan, so there is a theory that it was written by a descendant of Kim Chung-seon to honor his/her ancestors. A research performed by Chosen Sotoku-fu (Governor-General of Korea) produced revealed that it was not written by a Japanese and Sayaka was not a Japanese.
According to '慕夏堂文集', he landed on Busan Metropolitan City as a commander of the spearhead convoy of Kiyomasa Kato in April 1592, but immediately surrendered to the Korean side together with 3,000 soldiers (there is a description of 3,000 people in Dangun mythology, so it is assumed to be an expression to mean 'many'). Sayaka transmitted technologies such as matchlock guns and cannons and also fought against the Japanese army. After the war, he was given the name Kim Chung-seon to honor his achievement and he became a naturalized citizen. After that, he was promoted to 正二品 (senior second rank) for his achievement in suppressing the rebellion of Jurchen and he is seen as a hero in Korea. In 1992, a monument was built in the Republic of Korea.
Various theories
However, there is a theory that the credibility of the Sayaka traditions is low because no name of a corresponding major commander who was exiled exists in Japanese historical materials, he allegedly surrendered in the beginning of the war when Japan dominated, and Korea did not accept Japanese soldiers who surrendered (called 降倭 in Korea) but executed many during the beginning of the war.
Indeed, if he had an army of 3,000 under his direct control, among 10,000 soldiers of Kiyomasa Kato, he must have been a major vassal who had stipend off 60,000 koku (military service of five people per 100 koku was the standard) among 200,000 - 250,000 of Kiyomasa Kato's shoryo (territory), but it is too ambitious that such a major vassal switched sides in just one week after landing. Moreover, although he transmitted guns to the Korean army and fought against the Japanese army, the Korean army stood in front of the troop bearing firearms without taking much caution and was therefore destroyed with fusillade. They were too unprepared for the troops bearing firearms as they did not know much about fire weapons art.
Saika theory
An author, Ryotaro SHIBA, guessed that Sayaka was a transliteration of a Japanese name 'Saemon' that means 'Saika' in his essay, and Jiro KOSAKA wrote a novel stating that Sayaka was Saika on the same grounds. In addition, Chinjukan, who is said to be a descendant of Korean potters that were brought to Japan after the Bunroku-Keicho War, also supports this theory.
There was more than one commander whose name was 'Saemon' in Kiyomasa Kato's army, but they all returned. With regard to 'Saika', the Saika group indeed joined the Bunroku-Keicho War, and it was a local clan famous for the troops bearing firearms that once troubled Nobunaga. Furthermore, assuming that there was some enmity because they were later attacked by Hideyoshi, the actual fact could be maintained narrowly by rephrasing 'Sayaka with 3,000 soldiers' to 'Saika group with 300'. However, the Saika group who joined the Bunroku-Keicho War was the pro-Nobunaga sect that had lost in the private war against the anti-Nobunaga sect and it was a sect of Magoichi SUZUKI (see the Suzuki clan) who was protected by Hideyoshi later, making it a weak rationale. In another record, there is a description that indicates the character 善 in his name 金忠善 (Kim Chung-seon) may have also been in his Japanese name, and a person with a name 鈴木善之 (Yoshiyuki SUZUKI) in the Saika group was confirmed in Japanese records.
Okamoto Echigo no kami (Provincial Governor of Echigo, Aso no miya Echigo no kami) theory
It is also said that Okamoto Echigo no kami, a Japanese commander who actually surrendered and was in the peace negotiations for the Battle of Ulsan and the Battle of Juntenjo as an envoy of Korea, may have been Sayaka. The Aso clan, that was a local ruling family in Higo, was oppressed by Hideyoshi for triggering uprisings, and several years later, the family head Koremitsu ASO was murdered by Kiyomasa. There is a theory that he surrendered because he held a grudge. In addition, there is the Saika theory and a strange theory that assumes that Okamoto Echigo no kami was actually Magoichi Saika.
Nobutane HARADA theory
By building up circumstantial evidences irrespective of traditions, a commander called Nobutane HARADA emerges.
He, who was a senior vassal with 4,000 koku chigyo (enfeoffment) under the command of Kiyomasa Kato, was isolated in Tanchon and held up in a castle, but could not endure it and surrendered. Then (although there is a theory that he died of illness on the battle field in the Battle of Ulsan in 1598), the name Nobutane Harada suddenly disappears from records for a while, and when his family name reappears in the records, its chigyo was reduced to 1/10. Based on these, the theory maintains that Kiyomasa Kato kept a senior vassal's surrender a secrete and saved the Harada family by decreasing his salary significantly.
Theory of a Korean pretender
A theory that a Korean surrendered pretending to be a Japanese commander holding a gun which somehow helped him to be treated well. However, because many Japanese commanders and soldiers who surrendered were executed, there is a question why he pretended to be a Japanese taking a risk of being executed rather than being treated well.
However, to live as humble or lowly people, they may have needed such a 'Gishi' (forged history book). Even in the 19th century, the humble or lowly people 'Washu' were under harsh discrimination.
There are many other theories beside the above, but no theory has supporting records and there are many discrepancies with the tradition.
In Uronri in suburban Daegu Metropolitan City, the Republic of Korea, a family who proclaimed themselves as descendants of Sayaka still exist.