While the Nihon Shoki usually counts years by setting the year of accession of the Emperor or Empress as the first year, there are three instances where a separate era name is established. They are Taika (大化) , Hakuchi (白雉), and Shucho (朱鳥).
The Taika Era was set in 645 (Fourth year, sixth month, 19th day of Kotoku) at the official accession of Emperor Kotoku. It lasted until the Hakuchi period began on the March 22nd, 650 (sixth year of Taika, second month, 15th day). The Hakuchi Era continued until the death of Emperor Kotoku on November 24th, 654 (Fifth year of Hakuchi, tenth month, tenth day).
The Shucho Era was the first time in 32 years that the system of era names was reimplemented and began on August 14th, 686 (15th year of Tenmu seventh month, 20th day). However, with the death of Emperor Temmu in the same year on October first (15th year of Tenmu, ninth month, ninth day), use of this era name was discontinued in the following year.