Yang, 52, has had a long and storied career in fashion, image branding and creative consultancy.
In the 1980s, he had six different labels to his name, including The Island Shop at Tangs department store. These days, he designs costumes for theatre, including, most recently, the musical Forbidden City: Portrait Of An Empress in August and, prior to that, Beauty World in November 2015.
But his latest occupation is less about clothing people and more about unclothing culture.
The clutter in his house - and the moon goddess impersonation - is for an online project he started in August, in which he is posting a photo a day of himself in different get-ups for one year.
Called Face Of The Day, the photos include Yang as a national serviceman, Dracula, a Singapore Airlines stewardess, Egyptian pharaoh Tutankhamun, a hobbit and United States President Donald Trump. They are posted on Facebook, Instagram and www.faceoftheday.sg.
The project, he says, is meant to be "a visual dialogue" that aims to get people to look beyond the surface and think about their everyday lives.
Some of the posts, for instance, commemorate days and festivals, such as Chang'e's picture posted in celebration of the Mid-Autumn Festival. The captions for these posts include did-you-know facts about little-known aspects of each festival's origins and links to external articles or videos.
Other posts outline Singaporean cultural quirks, such as a picture in honour of "choping", in which packs of tissue adhere to Yang's face and shoulders; or one in which he is dressed as an "auntie".
Still others raise issues, such as a picture of a foodcourt tray perched askew on his head. "We are a smart nation full of smart people - why can't we return our trays?" he laments.
A team of about 20 of his friends and collaborators work on Face Of The Day, volunteering their time and resources for the project. They include professional photographers such as Geoff Ang, Jet Ho and Micky Wong; make-up artists such as Rick Yang, Grego and Zennie Casann; and playwright Michael Chiang, who writes content for the site.
About once a week, the team spends an entire day shooting anywhere from six to 16 looks. Shots requiring full body make-up, for instance, take more time than others.
Ms Casann, who does make-up for stage productions and fashion shoots, is happy to contribute her time, as well as her make-up and equipment, to the project.
She says: "I do a lot of commercial jobs. This project allows me to express myself without restrictions. It's not often that you can try so many looks and be inspired by all kinds of make-up. I've been able to push myself and learn a lot."
Yang makes many of the props by hand, such as a mask covered in pearls. "I have to glue the pearls on individually," he says.
Others are sponsored by costume shop Moephosis Concepts, which is owned by a friend. Still others are simply things he has lying around the house, collected from flea markets during his travels.
"It's not the easiest thing to find a Mexican sombrero. I had one from a party I had way back. I bought it about 20 years ago in Paris. I used to collect all sorts of funny hats from different parts of the world."
Other items in his collection include a Hussar military jacket purchased in London and a gongfu outfit acquired in Shanghai.
Relishing the job of people-watching
One challenge was hunting down a Singapore Airlines cabin crew uniform for a picture about the carrier's 70th anniversary this year.
"It's not easy to find a sarong kebaya in my size," he guffaws. "I wanted the blue one because I didn't want to be a chief stewardess, but the only one they had in my size was the red one. So I had to buy it."
He has also purchased rather a lot of things online - from sites such as Amazon and Taobao - as well as from second-hand shops around the world.
"The last thing I was trying to find was used golf clubs. I finally found them in Hong Kong," he says.
In September, he returned from a trip to London with 70kg of props, including hats and accessories.
He says: "I have spent, very happily, quite a lot of money on the project - more than $10,000 easily. It's quite an expensive pastime or hobby actually. But I'm thankful and grateful that I'm able to do that and enjoy it."
The project is his way of marrying social media, digital photography and art.
Each day's "visual dialogue", he says, should "make you think, laugh, cry, worry a little about something, reconsider something or reinforce a belief that you have".
The endgame of that, hopefully, is to "help you live a better, happier, saner life".
Too many people, he thinks, go through the busy motions of everyday life without really examining the world around them. But he has the capacity to remind them to do so.
"My day job is being a flaneur," he says, in a tone that makes it impossible to tell whether he is being flippant or serious. The French word refers to a man who wanders around the city making observations and originated with the French writer Charles Baudelaire.
Yang says: "I became a full-time flaneur at the end of last year, after Forbidden City ended."
And how much does being a flaneur pay?
"It doesn't pay in terms of the absolute monetary dollar," he laughs. "But it pays in terms of the knowledge and the vibe you get from just watching people and learning from them."
For more than 20 years, he says, he has been a "vagabond", working all over the world.
In 1987, he was talent-spotted by iconoclastic French designer Jean-Charles de Castelbajac - he of the famous teddy-bear coat sported by Madonna, who was collaborating with artists such as Andy Warhol and Keith Haring long before collaborations became the in thing.
Yang, who is single, spent seven years working in Paris as his style director. "Jean-Charles is an artist," he says, describing their days together as "crazy".
Then he was approached by international clothing brand Esprit to be its global image director and spent 12 years living in Hong Kong, New York City, London and Dusseldorf.
In a way, Face Of The Day can be seen as a collective snapshot of the zeitgeist of Singapore today, from the point of view of someone who is equal parts Singaporean and outsider.
"Having lived more than half my life abroad, I'm maybe able to observe it from afar. Hopefully, that lends a different perspective," he says. "The pictures are documenting and capturing that moment, person or topic that we live and go through."
And as someone from the fashion world, he knows that what one wears on one's face and body can communicate messages powerfully - that garb is a language in itself.
"All my life, I've been making clothes to cover up people or characters," he muses. Now, he is baring himself - at least, his face and shoulders - to the world.
One of Face Of The Day's Instagram followers, communications professional Jeanne Leong, says: "I like that it's subversive, slightly tongue-in-cheek and passive aggressive in the way he addresses issues - although it makes me slightly uncomfortable because I see a close-up of his face every day. But maybe that's his intention."
How many hours a day does he spend working on or even just thinking about Face Of The Day?
"You know," he says, his voice becoming huskier. "The funniest thing is that I can't stop thinking about it. I think about it all the time.
"If it's not the hair, then it's the outfit, the props, the set-up, the sequencing, how it's going to relate to Singaporeans or the rest of the world, and whether it's going to come across as offensive to somebody or some organisation. I don't stop thinking about it, actually, everywhere I go."
At the project's conclusion, he hopes to turn it into a photographic exhibition, art installation or coffee table book. And he invites anyone and everyone to join the Face Of The Day team.
"It's not just an asylum for a bunch of nutcases trying to do things. It's an open community of like-minded people who want to bring a little smile to everybody's face every day," he says.
"You're supposed to take Face Of The Day with a pinch of salt. A little twinkle in your eye helps you to live longer and better.
"The minute you know how to laugh at yourself, that is when you have reached a different level in your life. If you don't have humour, you have not lived."
His last post will be on Aug 4 next year.
Making more faces
On Aug 1, designer Yang Derong embarked on a Face Of The Day project, in which he posts a photo of himself daily in different get-ups, on social media and the website, www.faceoftheday.sg
