A California startup challenges a Japanese company to a battle for robot supremacy.

OAKLAND, Calif. — They’ve been popularized in movies, television and video games, but giant fighting robots still haven’t left the realm of science fiction. That will soon change.

Megabots, an Oaklandbased startup, has built a 15-foot mechanical gladiator called the Mark II and challenged a Japanese firm to an international battle for robot supremacy.

Tokyo-based Suidobashi Heavy Industries, maker of the 13-foot Kuratas, accepted the challenge, setting the stage for the first giant robot battle of its kind next year. The exact date and location are yet to be determined.

Win or lose, it’s all part of Megabots’ plan by to make gladiator-style robot combat into big-time entertainment — a mix between Ultimate Fighting Championship and Formula One auto racing — while developing industrial technologies and inspiring a new generation of engineers.

Megabots was launched in 2014 by Matt Oehrlein, Gui Cavalcanti and Brinkley Warren, who grew up playing video games like “Mech Warrior” and “Battle Tech,” and wanted to fulfill their dreams of watching massive machines fight.

Inside a workshop, the Megabots founders built the Mark II — a 12,000-pound behemoth with tank treads, two-pilot cockpit and missile launcher that fires cannonball-size paintballs.

Then Oehrlein called out Suidobashi in a YouTube video: “We have a giant robot. You have a giant robot. You know what needs to happen. We chal- lenge you to a duel.”

Suidobashi founder Kogoro Kurata accepted in his own video: “We can’t let another country win this. Giant robots are Japanese culture. Yeah, I’ll fight. Absolutely.”

The Megabots robot isn’t quite ready to take on Kuratas, a more polished fighting machine with a big, agile hand that mimics the movements of the pilot’s hand.

That’s why Megabots launched an online Kickstarter campaign and raised more than $550,000 from robot fans to turn the Mark II into a real fighting machine — faster, tougher, more balanced and equipped with detachable weapons such as a giant chain saw or punching fist.

The startup has enlisted the help of engineers from NASA, software maker Autodesk, and the TV shows “Mythbusters” and “BattleBots.”

Eric Risberg / Associated Press A crowd watches Megabots’ 15-foot-tall piloted Mark II robot in action last month at the Pioneer Summit in Redwood City, Calif. The Mark II even has a missile launcher that fires cannonball-size paintballs.