We conducted the third investigation at Meikakuji of Kyoto in March 2013, and found out private letters at the time of the India investigation by Ama Akira (Hashiramoto Zuishun). Based upon those letters, it was revealed that the solitary investigation in India (1907-1909) by Ama Akira was conducted before the Second Otani Expeditionary Party.
Since that is the fact which has been unknown before, those private letters are enormously valuable as historical sources. Also note that Hashiramoto Zuishun was the same person whose name was changed from Ama Akira; Enmeiin, one of the address, was the mother of Otani Kozui who dispatched the Otani Expeditionary Party; and Hashiramoto Zuiun was his father.