Meanings

age of a young lady who is at the peak of her (sexual) attractiveness

next century

Christian era

Devonian period

party discipline

rules which officials must follow

Carboniferous period

new era

Tertiary period

Empire Day (February 11th; national holiday held from 1872 to 1948)

the Kojiki and Nihon Shoki (earliest historical records of Japan)

relic from an earlier age

millennium

quarter of a century

decay (decline, corruption) of public morals

Rikkokushi (six national histories of Japan compiled in the Nara and Heian periods)

Citrus kinokuni (species of mandarin orange)

Permian period

Cambrian period

period