Stunt coordinator John Koyama plans out each fight scene for The Boys using cardboard, shooting a previsualization of what chaos is going to unfold.

“You use cardboard boxes as your background,” he says. “You use cardboard props. It’s a cardboard world.”

In one instance, a Tim Hortons’ coffee container became a machine gun. Showrunner Eric Kripke was so tickled by this process that it was written into an episode of the superhero show, which satirizes the world of entertainment, with “supes” — short for superheroes — rehearsing a scene alongside Koyama himself.

“It’s very cool because he paid homage to what we do in the stunt department,” Koyama says. The respect is mutual. Four seasons into the bloody Prime Video series, Kripke leans a lot on what Koyama, who goes by Koy, can come up with. In the early days, Kripke says he used to give detailed instructions on how fights should play out. Now, he lets Koyama’s imagination run wild.

Not that the writers don’t throw some curveballs Koyama’s way. Take, for instance, a sequence in episode two, where the vigilantes known as The Boys have to fight the supe Splinter (Rob Benedict), who can clone himself. The melee ends up at a bat mitzvah, and Splinter, along with his many doppelgängers, winds up butt naked.

The scene required a lot of VFX and necessitated that Koyama work closely with the set decoration and construction departments because of how much is destroyed over the course of the fight. But the most challenging part of the entire enterprise was finding performers willing to strip down.

“We were combing all of Canada,” Koyama explains. “It’s specific. When you find a stunt double, even when they are dressed, they have to be size-appropriate and look appropriate [in terms of] bone structure. And that’s with clothes on.”

The NSFW nature of the brawl also required careful choreography on Koyama’s part. While typically doubles can wear elbow and knee pads, in this case they were fully exposed.

“They’re falling and flying around fighting,” Koyama says. “You’re talking full frontal and appendages moving and how much you can get away with.” (For what it’s worth, the men were wearing prosthetics to hide their penises.)

Even when tackling a fight that is inherently ridiculous, Koyama tries to keep the action believable. At the same time, Kripke doesn’t like fighting to be too clean or to feel too planned. The John Wick movies have “beautiful ballets” of stylized gun battles, he says, but that’s not the aesthetic he wants for The Boys.

Koyama excels at “ugly” fights. Kripke cites a moment when The Deep (Chace Crawford) throws Annie (Erin Moriarty) into the ceiling and she lands on a desk.

“That’s just wire work,” Kripke says. “But the way [Koyama] crashes them into things and the velocity with which he and the wire riggers figure that out makes you wince, and that’s the goal.”

Koyama has a close relationship with the cast, many of whom execute some of their own stunts. In the fourth season, he joined their ranks playing, well, “Koy,” a stunt coordinator who meets a gruesome end after a supe sends him flying into the side of the building. Despite the character having Koyama’s name, Amazon required him to audition for the role.

Luckily, he landed the part.

This story first appeared in a June stand-alone issue of The Hollywood Reporter magazine. To receive the magazine, click here to subscribe.