The calendar used by the Empire is measured in days and years roughly the same length as those on Earth, though calculations by the JSDF suggest that a year in Empire is slightly longer than one on Earth.
The Imperial Calendar has an unspecified number of months, of unspecified day length, with names such as the "Month of Fog".
The Common Era known as Earth Calendar or Calendar of Earth used know at AD by All Nations of Earth and its was adopted in the late 16th century CE on Earth. The first year of the calendar, 1 CE, was the estimated date of the birth of Jesus Christ, an important religious figure in ancient history to used at AD by modern-day time on Earth like early 21th century CE. Has unspecified number of months, of unspecified day length, with name such as "the Day of the week,month and years.like Tuesday July,7,20XX AD CE."
The Imperial Calendar can be presumed to begin at the founding of the Empire. The JSDF arrival in 20xx is concurrent with the Imperial year 687. While little is known of the precise history of the Empire, the following dates in Imperial history, as well as character birthdates are known. As the official date of the Japanese-Empire War is listed as 20xx, but clearly in the early 21st century, the year 2016 has been used to estimate the real-world equivalent of the Imperial Calendar year.
- IC -274 (approximately 1055 CE): Birth of Rory Mercury
- IC 0 (~1326 CE): presumed founding of the Empire
- ~187 IC (~1429 CE): Downfall of the Kingdom of Arrun
- IC 372 (~1701 CE): Birth of Yao Ro Dushi.
- ~IC 437 (~1766 CE): The Empire fought a major conflict known as the Arctic War, which was generally considered one of the most trying times for the Empire.
- IC 522 (1851 CE): Birth of Tuka Luna Marceau
- IC 671 (~2000 CE): Birth of Lelei La Lalena
- IC 680 (late 2000s CE): A rebellion in the Empire was suppressed. Grey Co Aldo served in the conflict.
- IC 684: Zorzal El Caesar attacked the Warrior Bunnies, starting a short but bloody war which ended with the genocide or enslavement of most members of the Warrior Bunny tribes.
- IC 687 (early 21st century CE):
- The Empire invaded Ginza, Tokyo, Japan, through the Gate, only to be easily defeated by the Japan Self-Defense Forces, starting the Japanese-Empire War. The JSDF's counter-attack through the Gate were victorious within a few months of the incident known as Battle of Ginza and This would later be known as the "The Ginza Incident" and its Starting at 03:40:50 to 17:56:50 on August 20XX,GMT is That of times and days when Japanese-Empire War Started at.
- The Imperial Civil War Begins during Japanese-Empire War and its is when Zorzal and his cohorts manage to inflict some damage to the JSDF due initial stage by conducting guerrilla warfare by disguising Imperial Troop as refugee to sabotage JSDF operations And Starting the civil war between Zorzal's pro-war force and the Empire pro-peace faction led by Pina as well as the JSDF. During the war,
- Both the Japanese-Empire War and the Imperial Civil War end with Zorzal's death and peace between legitimate Imperial government and Japanese government.
- After end of the Japanese-Empire War and the Imperial Civil War with Zorzal's death and After the Gate opens to the homeworld of the Arachnid, the Hive Mind of the Arachnid commands its Warrior Bug to attack the Special Region the Arachnid War its started between the JSDF and the Empire against the Alien bug that invades the Special Region to consume its biomass and resources.
- After the Archnid manages to slaughter thousands of citizen of the Empire as well as JSDF. Lelei forces to close the Gate to prevent more calamity.