On Monday morning, a senior government official in Tokyo will enter a room, gather his thoughts and hold up a work of handwritten calligraphy.

Millions of people will pause and digest the meaning of the two kanji characters, and Japan will finally get the answer to a question that has kept it in suspense for months: the name of the new imperial era.

The characters will open a new chapter in Japanese history, a month before the emperor, Akihito, makes way for his eldest son, Crown Prince Naruhito, whose enthronement will take place on 1 May in the country’s first imperial abdication for 200 years.

Symbolism aside, there are compelling practical reasons behind the decision to reveal the name of the new era weeks before the new emperor begins his reign.

Japanese officialdom, companies and many citizens use the name of the imperial era – or gengo – to mark time, often in tandem with the Gregorian calendar. The era’s name appears on everything from official forms and identity documents to coins, calendars and newspapers, as well as being used in everyday conversation.

Emperor Akihito stands as court officials hand over the sacred sword and jewel, symbols of the emperor, at the enthronement ceremony in 1989. Photograph: AP

Under the system, which spans several centuries, 2019 is known as Heisei 31, or the 31st year of Akihito’s reign.

The early announcement will give companies and public bodies time to incorporate the new era’s name into their paperwork and computer systems, and avoid any Y2K-style glitches when Naruhito becomes emperor on 1 May. Local governments say they have been preparing for the change for months and are confident they will be able to update their records in time.

In Minato ward, a densely populated part of central Tokyo, officials are poised to cross out the current era’s name on thousands of documents and stamp the new one above it, while companies including Fujitsu and NEC have been helping clients ensure their computers don’t crash as soon as the new era begins.

The names given to Japanese imperial reigns can have far-reaching consequences. The choice of characters can help determine the national zeitgeist and, over time, the name becomes a byword for collective memories of the era in question.

The Meiji (enlightened rule) era of 1868-1912 is remembered as a period of western-inspired modernisation; the Showa (enlightened harmony) era, which began in 1926, is closely associated with Japan’s economic rise, but also with its role in the second world war.

The three decades of Heisei (achieving peace) evoke similarly ambivalent feelings: it was the end of the bubble economy, a time of rivalry with China and several national tragedies, including the 1995 terrorist attack on the Tokyo subway and the disastrous earthquake, tsunami and nuclear accidents of March 2011.

“It is easier to imagine what the time was like if you have eras,” Kunio Kowaguchi, the president of calendar maker Todan, told Agence France-Presse. “For instance, we remember it was early Heisei that the economic bubble burst.”

It remains to be seen if the new era will revive the popular use of gengo amid a preference for the Gregorian calendar. A recent poll by the Mainichi newspaper found that 34% of people used gengo most of the time, a similar proportion used both in roughly equal measure, while a quarter preferred the Gregorian calendar. In 1975, 82% of people said they used gengo more frequently.

The honour of revealing the name will fall to the chief cabinet secretary, Yoshihide Suga, despite speculation that the announcement would be made by the prime minister, Shinzō Abe.

In 1989, one of Suga’s predecessors in the role, Keizō Obuchi, sealed his place in Japan’s modern history when he proclaimed the name of the current era, Heisei – a single act that left a deeper impression on the public than his time as prime minister.

Abe, though, may yet find himself closely associated with the change. One of the characters widely tipped for inclusion in the new era’s name also appears in his surname.

But the panel of experts tasked with devising a shortlist of contenders – with the cabinet to make the final decision – will be eager to avoid accusations that their choice has political overtones, given the constitutional ban on postwar emperors from wielding political influence.

As speculation mounts, one thing is certain. Akihito’s reign will end on 30 April, and with it the Heisei era. The following day, a new era will begin as his son becomes the 126th occupant of the Chrysanthemum throne.

Crown Prince Naruhito and Crown Princess Masako greet guests at garden party in Tokyo. Photograph: Kazuhiro Nogi/AFP/Getty

How the name is chosen

No one, other than a close-knit group of experts and politicians, will ever learn the identity of the man or woman behind the name given to Japan’s new imperial reign.

For the past few months, a secretive eight-member panel of experts, including scholars of Japanese and Chinese classical literature, has been debating the merits of scores of possible names for the new era, the latest of almost 250 gengo stretching back to the seventh century.

On Monday morning, Suga, the chief cabinet secretary, the leaders and deputy leaders of both houses of parliament along with representatives from business, academia and the media will meet to discuss the shortlist, with the cabinet left to make the final decision.

In the past, emperors would change era names mid-reign to foster a spirit of renewal after natural disasters or crises; more recently, a single era has been used to mark the entirety of a monarch’s time on the Chrysanthemum throne.

Tradition dictates that the new name must have two characters, be easy to read and write, and not be commonly used. It is also unlikely to start with the first character of any of the last four eras: Heisei, Showa, Taisho and Meiji.

Everyone involved in the final stage of a process that has been rehearsed annually since the Akihito’s reign began 30 years ago is sworn to secrecy.

To prevent leaks, they will have to surrender their mobile phones before the final deliberations begin and remain in a room until Suga unveils the new era’s name – written in traditional sumi ink on decorated shikishi paper – on live television.