In mid-February, Thailand's King Maha Vajiralongkorn invited his subjects to dress up in 19th century court costumes to celebrate a "winter fair." For several weeks, Dusit, the historic Bangkok neighborhood that includes Chitralada Palace, the monarch's official residence, was transformed into a living pageant.
Thailand's governing military regime grabbed the chance to burnish its patriotic credentials, led by Prime Minister Prayuth Chan-ocha, the junta's supremo. Prayuth showed up all smiles on a tropical afternoon at Royal Plaza, a major public square, wearing a light-purple silk top and sash over a pair of puffed and shimmering pantaloons.
As a long-time resident of Dusit, none of this struck me as odd. I have grown accustomed to displays of pomp and ceremony in this traditional neighborhood of tree-lined avenues and quietly flowing canals. It is common to run into Thais dressed for official occasions in attire designed to embrace the historical social order of this semi-feudal country.
The costumes also look quite natural in an area that hosts the Chitralada Palace, the Ananta Samakhom Throne Hall, a regal, European-style reception hall, and Vajiravudh College, an elite school with distinctively Thai cascading roofs.
But the latest burst of fancy dressing has its roots in a wider enthusiasm for costume play sparked by the roaring success of a Thai soap opera called Bupphaesannivas (Love Destiny), which is set in the 17th century during the reign of King Narai the Great.
Supaporn Watiboonruang, 28, who works in marketing in Bangkok, is one of thousands of Thai women who are slipping into shimmering silks and long shawls, draped diagonally across the shoulders, just like the female lead in the soap opera. Many make family trips to the ancient royal city of Ayutthaya, about 80km north of Bangkok, to pose for photos against the backdrop of Wat Chaiwattanaram, a Buddhist temple featured in the drama. Ayutthaya, now a UNESCO World Heritage Site, was home to the monarchs of Thailand, then known as Siam, for 400 years until 1767, when it was destroyed by a Burmese army.
The most common explanation for this national cosplay surge is that the soap opera has touched a chord among the viewing public, encouraging people to dress up in clothes they like but rarely wear.
Some cultural commentators put it down to a romantic reading of Thai history -- a trait shared with many Asian societies that view with nostalgia the supposedly more innocent societies of previous centuries.
Either way, the costume boom is a bonanza for Prayuth and his generals, dovetailing neatly with their ultra-patriotic message, which stresses unity and uniformity as solutions to Thailand's political divisions. In trying to tap this zeitgeist, the junta is preparing to spend millions of baht to finance a sequel to the soap opera.
The regime has also suggested that officials should wear period costumes to work to encourage the country to march in cultural step. The public might be urged to follow suit.
Some businesses have already climbed on the bandwagon, including Thai Airways, the national carrier, which has told its flight attendants to dress in 19th century royal court style, and a Bangkok massage parlor that requires its women to sport the Ayutthaya court style as they sit in their glass-walled premises, waiting for clients.
But this retro-fashion fever holds out weightier possibilities. Will it stir historical interest in the former royal capital? That would be an important cultural development. Ayutthaya was, as UNESCO puts it, a center of economics and trade at the regional and global levels, and a connecting point between East and West.
In Thai culture, Ayutthaya has been largely overshadowed by the northern town of Sukhothai, the first capital of Siam from the 13th century, which is seen as the birthplace of Thai art, architecture and language.
Thai-based scholars are beginning to challenge that view. Chris Baker and Pasuk Phongpaichit, for example, present a window into the city's thriving commercial and cosmopolitan life in their recent book, "A History of Ayutthaya: Siam in the Early Modern World."
Up to now, however, the country's open, successful and diverse second capital has been relegated to the margins of Thailand's national history. If cosplay helps Thais to turn that page, then the current fashion for nostalgia may prove to be more than just skin deep.
Marwaan Macan-Markar is an Asia regional correspondent of the Nikkei Asian Review. He is based in Bangkok.