According to the diary of priest Gikan who always joined the army with Prince Yoshihisa, it is known that terms used for the emperor have been applied to Prince Yoshihisa since around April, and thus it can be assumed that he ascended the throne when he was put up by shogitai or at least accession to the throne was scheduled.
親王に常に従軍していた僧義観の日記からは、四月頃からすでに用語などは天皇扱いであったことが知られ、彰義隊に擁立された頃には践祚したか、少なくともその計画があったことが推測できる。