Japan's new emperor Naruhito begins his reign with a ride befitting royalty because he's commissioning a unique, open-roof Toyota Century, according to The Wall Street Journal. While reports stated that he intended to use the vehicle upon becoming emperor on May 1, there was no sight of it. Look forward to seeing the custom Century at a future event.

Gallery: 2018 Toyota Century

It's not yet clear what the open-roof Century looks like. Completely re-engineering it to have a massive convertible top seems like too expensive of an undertaking – even for such a prestigious client. Having no top at all is one option, or Toyota could opt for a layout similar to the Lexus LS 600h L Landaulet (below) from the company's cooperation with Belgian coachbuilder Carat Duchatelet for the wedding of Prince Albert II of Monaco and Charlene Wittstock.

Gallery: A very royal Lexus LS 600h L Landaulet revealed [video]

The Century is Toyota's range-topping model and is exclusive to Japan. Prices start at 19,600,000 yen (£135,000 at current exchange rates), and the company builds just 50 of them by hand each month. Power comes from a hybrid 5.0-litre V8 with a combined output of 425 bhp. The cabin coddles rear passengers with amenities like an 11.6-inch entertainment screen, and 20-speaker stereo.

Naruhito has good company because Toyota CEO Akio Toyoda also rides in a custom Century. Rather than an open-roof version, the boss' example has a sporty tune from the company's Gazoo Racing performance division. The company isn't very open about the tweaks to this model, but the obvious changes include a more aggressive body kit, boot lip spoiler, and larger wheels. Rumours suggest that it might be all-wheel drive, rather than the standard rear-drive layout.