Takashina no Tonari _??__??__??__??_ is well known to those who study Kukai as the government official in charge of the ship Kukai used to return to Japan. Researchers on Japanese official voyages to Tang China strongly suggest that Tonari led the fourth mission to Tang in the Enryaku period, and although this theory is widely accepted there are no conclusive documentary records to support it and contrary theories appear from time to time.
Accordingly, there are the theories that he was re-dispatched according to Kaido no Rei _??__??__??__??_ (TAKAGI Shingen), and recently that the fourth ship embarked a year later (UEDA Takeshi, TAKEU CHI Kozen).
A major factor behind these various theories is that in the Nihon koki _??__??__??__??_ entry for the sixteenth day of the seventh month of 805 notes that the third ship with Mimune no Imatsugu _??__??__??__??_ was shipwrecked. This entry could be (1) misplaced here from the section for 804, (2) it could be that the return voyage is meant, or (3) the views of earlier articles, but there is no consensus.
In this paper I trace the historical changes in the diplomatic voyages to Tang, and while afterwards explaining the position of such diplomatic missions at the time show that the possibility of re-dispatching a mission or repeated negotiations is extremely low.
Along with a discussion of Tonari's background, I describe his relationship with the functional head of the government office at Dazaifu (Dazai no Daini _??__??__??__??_) Fujiwara no Kadonomaro during the time from when Tonari was third minister of Dazaifu (Dazai no Daigen _??__??__??__??_) until he was appointed to the voyage diplomatic staff, and the strong likelihood that the passage stating that he was “suddenly appointed to the mission, and did not even have time to prepare for the voyage” (Nihon hoki fragment) refers to the time immediately prior to the urgent re-departure of the mission in 804, when the ambassador Kadonomaro, his former superior, requested his participation.