According to "Nihonshoki" which was compiled at the beginning of the eighth century, the accession of Emperor Jinmu was on 'the first day of the first spring month of the year Kanoto-Tori,' that is, the first of January.
8世紀初めに編まれた『日本書紀』によれば、神武天皇の即位日は「辛酉年春正月、庚辰朔」であり、日付は正月朔日、すなわち1月1日となる。