When Japan's Hirado Castle gave a free overnight stay to a group of guests in 2017, it soon received 7000 applications from others wanting to do the same.
Now the castle, in the Nagasaki Prefecture, has officially opened for over-nighters, joining other off-piste locations in Japan offering new, unique stays.
While the Japan Tourism Agency says only 300 of the approximately 77,000 temples in Japan - and even fewer castles - offer accommodation, the authority is encouraging travellers to seek out these regional attractions as places to stay. These offer a not insubstantial side benefit of sustainability, as Japan's castle and temple lodgings are mostly in locations rarely visited by tourists.
Wakayama prefecture has a remarkable concentration, with almost half of its 100 temples offering accommodation, allowing visitors to experience daily temple life, including meals, prayers and meditation.
The Eiheiji Temple in Fukui Prefecture is one of the two main temples of the Soto school of Zen Buddhism, the single biggest denomination in Japan. This important religious site is also home to the Hakujukan hotel, offering a "soothing stay" via a combination of ryokan and retreat.
"Zen Concierges", trained at the temple, provide guests with guidance before inviting visitors to relax in the open-air baths and enjoy vegetarian Japanese cuisine and local sake from Echizen at the onsite restaurant.
And if you haven't started planning your 2022 Japan sojourn yet, now might be the time, with all signs emanating from the federal government that Japan and South Korea may soon follow Singapore's lead and open their borders to Australians.
While It remains to be seen if Australians are ready to head into Tokyo's famous capsule hotels, with their high densities and teeny hallways, there is a whole other natural and rural side to Japan outside of its teeming cities, where COVID-weary travellers will find the space, serenity and safety they seek.
At Hirado Castle, only single groups of guests can stay on any one night, allowing them to have the castle to themselves. It doesn't come more COVID-safe than that.
For information on temple and castle stays the official Japan tourism website includes valuable information noting that some of the more traditional facilities don't take credit cards.