Teams from 36 countries and regions faced off in central Japan on Saturday, having faithfully recreated the elaborate outfits, colourful hairstyles and all-important attitude of their chosen anime, manga and video game stars.
The championship is part of the World Cosplay Summit in Nagoya, a three-day event that draws thousands of fans -- many keen to show off their own costumes.
"People really commit to cosplay competitions," said Lettie Shiels from Britain, who won last year's contest with her teammate Claudia Maw.
"We're not just talking about weekends and evenings -- I probably averaged about four hours' sleep for a good number of months," she told AFP.
The pair, who go by the stage names Tsupo and Clood, met in cosplay circles over a decade ago and have seen their hobby transform from a crafty, DIY subculture into a global phenomenon.
Perfecting self-taught skills from make-up artistry to prosthetics, dressmaking and prop design is a key part of cosplay, a combination of the words "costume" and "play".
In Nagoya, contestants are judged on the accuracy and quality of their costumes.
"They go pretty hard on that. You have a reference picture, and everything has to be exactly the same. If anything's missing, you'll have points docked," Shiels explained.
Then they must perform a two-and-a-half minute skit in character, which former champions Tsupo and Clood have been invited back to Japan to judge.
"I want to feel immersed. I want to feel like they love the source material," which will shine through in the choreography, acting and visual effects, Shiels said.
'Smiling inside'
Braving the mid-summer heat and humidity, crowds of Japanese and international cosplay enthusiasts throng the city centre for the annual event, which was first held in 2003.
Characters from top manga comics such as "Naruto" and "Slam Dunk" pose for photos next to others in full-body get-ups, including the fantastical mechanical fighters from "Gundam".
There are some ground rules: gore such as bloody wounds and bruises is forbidden, as well as costumes that show too much skin or underwear, and any real-life uniforms.
Behind the scenes ahead of the performance round, the pressure is on for the national teams, each formed of two competitors, who have squeezed all their homemade gear on to international flights.
Each team is picked at national heats, similar to Eurovision, and this year cosplayers have travelled from places including France, South Africa, India, Mongolia and Thailand.
In one of the shared dressing rooms, Irina Tsapreva of Bulgaria, dressed as a character from "Mononoke", is busy affixing realistic looking pointy ears to her partner.
"I love many things about cosplay. First of all, I have always loved carnivals and dressing up, so this is like a holiday for me," said Tsapreva.
She has a master's degree in theatre costume design, which helps when embroidering her costume with silk and creating everything else from scratch, including assembling traditional wooden Japanese shoes.
But many other competitors have varied day jobs, from a kindergarten teacher to a healthcare innovation worker.
Cosplay began as a hobby but is becoming more serious for Henrik Pilerud, who has created a huge, smiling, "Totoro" creature with moving eyes from the classic 1988 Studio Ghibli movie "My Neighbour Totoro".
"We chose this because it is beloved and it's so iconic," the Swede said.
Even though it's uncomfortable inside the furry shell, "people are smiling and being happy," so "you forget all the heat and the weight, and you're just smiling inside here as well".
