Yinyuan was asked to stay in Fumonji 普門寺 in Osaka for six years. One explanation for this long detention was that he was suspicious of being a Chinese spy. However, I didn't see any primary sources directly accused of him or providing any evidence. My personal view is that it was highly unlikely that he had this secret mission. The first question is who he worked for. He could not work for the Manchus. Then he must have worked for Zheng Chenggong 鄭成功 whose ships escorted him to Nagasaki. Then why Zheng Chenggong wanted to spy on Japan.
This spy theory may have something to do with Mukai Genshō 向井元升 who criticized Yinyuan in his Chishihen 知恥篇. I analyzed his essay in Chapter 6 of my book. He knew that Yinyuan had sent his disciples to contact his teacher Feiyin Tongrong who was in the Hangzhou area around that time. He surmised that because the Hangzhou area was occupied by the Manchus, their frequent communication must have divulged information about Japan. Kumazawa Banzan 熊沢蕃山 shared a similar view. (For this discussion, see my book, Leaving for the Rising Sun, page 182.)
However, in the eighteenth century, when the Qing dynasty secured its power, both Kangxi and Yongzheng sent spies to Japan. Kangxi sent a certain Manchu official Mo'ersen 莫爾森 from Hangzhou Silk Manufacturing Office 杭州織造. (Prof. Lynn Struve was very curious about his identity and is researching on him.) Yongzheng's Zhejiang governor Li Wei 李衛 sent Zhu Laizheng 朱來章. The suspected spy ship according to Oba Osamu is the Siamese Vessel no. 2 of the year Kyoho 14 (1729). Oba did mention a Chinese monk who was an informant and Zhu Laizheng obtained useful information from him. (Oba, Books and Boats, pp. 234-235.)
|Chinese monk Quanyan Guangchang's tomb at Fukusaiji © Jiang Wu|
This monk's name is Quanyan Guangchang 全巖廣昌, the sixth abbot of Fukusaiji 福濟寺. I mentioned him briefly in my book page 224, and his possible espionage activities in page 295, note 30. We know quite a bit about him because Ka'i hentai 華夷變態 has preserved the affidavit he submitted to the Nagasaki officials when he arrived at Nagasaki from China. His full biography can be found in Obaku bunka jinmei jiten 黃檗文化人名辭典, pages 185-6. I visited Fukusaiji during the summer of 2013. Although the old temple structure was completely destroyed by the A-bomb, Quanyan's memorial pagoda remains there.