His formal title is His Imperial Majesty the Emperor, Akihito, who succeeded to Japan's Chrysanthemum Throne upon the death of his father in 1989.
Now, the 84-year-old Akihito is giving up that noble seat, officially abdicating in 2019. When he goes, it won't just signal the end of a decades-long reign, and the first time in centuries an emperor has surrendered his post. The effects could reach far beyond that.
When Akihito relinquishes power, his stepping down might in fact trigger a technological meltdown felt throughout Japan: a kind of Y2K 'millennium bug' encoded within an ancient dynasty that traces back almost 3,000 years.
Akihito is regarded as a direct descendant of Japan's first emperor, Jimmu, who reigned – so legend tells us – from 660 BCE, succeeding the Age of the Gods in Japanese mythology and ushering in what is called the Human Age.
Jimmu's historic accession to the throne is now regarded as legendary by Japanese scholars, but some 1,300 or so years after the time of his mythical rule, 'modern' emperors of the 7th century began to have their imperial reign marked by a unique, separate calendar system, denoting the era of each emperor.
This tradition, which continues to this day in Japan (alongside conventional use of the Gregorian calendar), means we're currently in the Heisei period, the era corresponding to the reign of Emperor Akihito. Until next year, that is.
This is where the technological meltdown comes into things.
When Akihito abdicates in April, his son Naruhito will assume the throne, and Naruhito's reign will usher in a new Japanese era to succeed the Heisei period.
The problem is, Akihito's own reign has spanned almost the entirety of the modern internet era, and when a new (and still unnamed) calendar system kicks into effect in 2019, there's a chance this unprecedented, untested technological transition could make all kinds of computer systems go haywire.
"Several sectors could face troubles like the postal service, transportation ticket vending machine, and banks," independent researcher and analyst Anne-Léonore Dardenne told Digital Trends.
"For example, the record of tax payments could be problematic… It might also be impossible to withdraw money from ATMs. The Japanese calendar is used in almost every official document. For political reasons or cultural reasons, the government, public agencies, and financial institutions all use this calendar."
The potential severity of the situation has been acknowledged by Microsoft, which internally describes the transition as the "Japanese Calendar's Y2K Moment".
"Fortunately, this is a rare event, however it means that most software has not been tested to ensure that it will behave with an additional era," Microsoft software engineer Shawn Steele explained in a company blog post in April this year.
"The magnitude of this event on computing systems using the Japanese Calendar may be similar to the Y2K event with the Gregorian Calendar."
For its part, Microsoft is building in 'placeholder' code in Windows 10 so that the software can accommodate a new imperial era, but innumerable other technological platforms also need to adjust.
One such is Unicode – the body that oversees text character standards across countless technological and programming languages.
It's got to somehow figure out how to incorporate a specific character for Naruhito's impending era for immediate testing – even though Japan has indicated the name won't be released until next year.
"The [Unicode Technical Committee] cannot afford to make any mistakes here," Unicode technical director Ken Whistler explained in a post last week, "nor can it just guess and release the code point early."
The inevitability of these hurdles is something technologies – if not imperial dynasties – habitually face.
"Technologies capture a moment in time," technology historian Dylan Mulvin from the London School of Economics explained to New Scientist.
"For many good reasons, software can't be written with every contingency in mind."
That's true, and while workers in the IT industry both within Japan and outside of it grapple with how to counter this looming issue, it's also worth remembering that the Y2K problem – aka 'the Millennium bug' – never actually ended up being anywhere near as bad as pundits feared, and hopefully that's the case again here.
After all, for a nation who once emerged out of a divine abdication of power from gods to mere mortals, Japan has probably got this.