"Heisei," the name of the current era, means "achieving peace" and began on Jan. 8, 1989, the day after Emperor Hirohito died.
Previous era names in modern history have been Meiji (1868-1912), Taisho (1912-1926) and Showa (1926-1989), followed by the current Heisei era.
Japan's imperial era system, however, is not without its critics.
Some maintain the Gregorian calendar should be used as the country's standard, with others stating that the antiquated system no longer reflects modern Japanese society.
"(Society here) is no longer controlled by an emperor," Hiroshi Kozen, a Chinese literature professor emeritus of Kyoto University and a member of the Japan Academy, told Kyodo News.
"The era system should reflect people's desire and we have to start from discussing why we need it," the 82-year-old was quoted as saying.
Others, including legal entities that filed a lawsuit last week at a local district court to try and scrap the "gengo" system, believe it violates the Constitution.
The era name changing with each imperial succession "destroys a sense of time held by each individual and violates Article 13 of the Constitution that guarantees all of the people shall be respected as individuals," the plaintiffs of the suit were quoted as saying.
Emperor Akihito will step down on April 30, marking the first Japanese monarch to abdicate the throne in about 200 years.
The 85-year-old emperor, Japan's 125th according to the traditional order of succession, expressed his desire to step down in a rare video message broadcast in 2016.
During the video message he expressed his concern that owing to his age he might not be able to fulfill his official duties.
A year later, the parliament passed a one-off bill enabling Emperor Akihito to step down.
The government ordinance on the new era name will be promulgated as early as Monday afternoon following its signing by Emperor Akihito.