"I thought 'I could just about wear that'," she said, and that thought proved to be a catalyst that has seen her tap into an international niche market.
Her business 'Sparky Can Do' specialises in "custom-made fursuits" – to say I was intrigued is probably an understatement.
Driving to her rural property in Carterton, I wondered how many other people were as oblivious as I was to the magic happening inside her house, which looked just like any other rural Wairarapa property.
Johnston welcomed me into her work room and I was immediately blown away.
Various sewing machines, her own 3D printer and rolls of high quality fur fabric lay among the impressive costume pieces still in progress.
She told me about how she gradually built up her machinery as her business progressed after the initial idea, which she finally followed up when she was working in the vineyards.
"When the season was down, my fiancé at the time [now husband] financially supported me while I made three partial costumes.
"I posted an online auction and they were all bought up within one to two months for $500 each.
"That's when I thought, 'hey, I could make some money here'."
She has now been selling full fursuit costumes for around seven years, making one per month to meet the demand, but allowing her enough time to complete them to a high standard.
She avoids having long waiting lists by posting an online auction each month.
"People bid for that spot to have a costume made," she said.
"That way there's never a waiting list and people are paying top dollar for my costumes."
Her most recent auction reached $9500, with eight hours of bidding time remaining.
The most she had ever sold a costume for was $11,500 – pretty impressive for someone who was self-taught via internet videos.
Johnston requires the winner of each auction to send her an artist's depiction of the design they want, which shows the kind of creature they would like and the colours and patterns they want on the fur.
Some clients design their own hybrid creatures, such as a dragon morphed with a fox.
"They all come up with their own fursonas and I bring them to life."
She also gets her clients to provide a duct tape dummy, or doll, by wrapping their entire bodies in tape to ensure they get a perfect fitting.
Her costumes are sought after by clients from the United States, Australia, Germany, Belgium and Japan.
Part of the demand is spurred on by her massive YouTube following, who watch her video tutorials on fursuit-making, as well as documenting her own fursuit adventures in her 'fursona' called Sparky.
"I went skydiving in this," she said laughing, as she showed me her costume.
Johnston hand-sculpts clay teeth, hand-stitches the head pieces, and does her own 3D printing to create the internal elements of the head pieces.
She has a staff member who is learning the craft and assists with making the body suits, while Johnston focuses on the intricate head pieces – some of which come with functioning mouths that open and close as the wearer speaks.
We both laughed as I asked the awkward question of what kind of people wore the costumes, and whether or not this was a fetish thing.
Johnston explained there were fur communities all around the world, made up of regular people who were living out their childhood fantasy of being an animal and attending "big party conventions" together.
"They're people who want to have fun – they run around playing and pretending to be animals.
"It's returning to that playful kid state.
"They have games and race each other – they even have egg and spoon races."
She said only around 20 per cent of 'furries' had costumes and the conventions were also attended by non-costumed anthropomorphics.
"You can be a furry without a costume – the rest go for the people, the atmosphere and the art."
Her plans for the future meant she may have to scale her business back slightly, as she and her husband want to travel around the country in a house bus by the end of the year.
However, she will remain committed to her furry followers, and plans on making partial costume pieces while out on the road.
