The creators of “Avatar: The Last Airbender” say that the new spinoff series “The Legend of Korra” will be more mature than the original show, but will still have the same sense of fun and adventure.

Nickelodeon, the network behind the original show, today announced that it will air the “Avatar” spinoff series “The Legend of Korra” (a working title) starting next year.

The first series took place in a world in which supernatural “benders” have the ability to manipulate the elements of air, earth, fire and water, and focused on Aang, a young airbender who turned out to be the Avatar, a person capable of controlling all the elements. The new series takes place 70 years later in the same world and follows the new Avatar, a teen girl named Korra who has learned to bend earth, water and fire and seeks to master air under the tutelage of Aang’s son, Tenzin.

Earlier this summer, director M. Night Shyamalan released a live-action theatrical version of the first series called “The Last Airbender” that was poorly received by critics, although it posted respectable numbers in early box office returns.

Michael DiMartino and Bryan Konietzko, the creators of “Avatar: The Last Airbender” and “The Legend of Korra” took the time to talk to Speakeasy today about the new series.

The Wall Street Journal: How did you come up with the idea for the spinoff?

Bryan Konietzko: When Mike and I first created “Avatar: The Last Airbender” we always knew it would have an ending to it, that particular story. But as the show really took off, and found an audience all over the world, we knew that despite our intentions of ending that story there would probably be a time when Nickelodeon would come calling and want some more episodes….When that time came we had this idea for jumping ahead and telling a story about the next Avatar, this girl Korra.

If there’s a new Avatar, that means Aang has passed on. If he died around age 70, isn’t that pretty young for an Avatar?

Konietzko: You gotta keep in mind that he was frozen in a state of suspended animation for 100 years, so he kind of burned up some of his extra Avatar time.

The new “Avatar” is a woman. What inspired you to change the sex of the protagonist of the series?

Michael DiMartino: It’s not so much about changing because we had Avatar Kyoshi before Aang. We’d established that the Avatar can be male or female and we just thought let’s explore one of those more in depth, because Kyoshi was a popular character with a lot of fans and it seemed like a great opportunity to not retread what we’d done with Aang, who was a great hero, we all loved him, but we really wanted to try something different. And we have so many great female fans out there, who really responded to Katara in the first series, we thought we have the fan base who are really going to enjoy seeing the Avatar be a female.

Konietzko: Mike and I, we love those characters too, and we’ve encountered countless fans who are male who really like those characters too. We just don’t subscribe to the conventional wisdom that you can’t have an action series led by a female character. It’s kinda nonsense to us.

The one image that you released is Korra looking out on Republic City, where a lot of the new show take place. Tell me about that city.

Konietzko: That’s kind of a piece of concept art so when the show premieres next year it won’t look exactly like that but that’s the direction we’re headed. The first series was sort of a road show where every episode they were going to some new location. That was another new thing we wanted to do is root it in one big complex location but mainly one place. We were drawing inspiration from Shanghai in the 1920s and 30s and Hong Kong and even Western cities like Manhattan and even location-wise cities like Vancouver, a city that juts out on a peninsula or an island and has these big mountains around it.

Will we see characters from the previous series pop up?

DiMartino: I don’t want to give anything away, but rest assured there’s a definite link between the old series and this one.

Republic City is a city plagued by crime. There’s an anti-bender revolt. Does this new series deal with more mature themes?

Konietzko: Mike and I like a balance of tones. We never set out to make an overtly silly show or an overly serious dramatic show. We like dealing with all those things. It’s fair to say we’re dealing with some sophisticated things and the show is growing up a bit. But that said, we’re not in a calculated way trying to target another demographic. Even in the first series, it was about a world war and some pretty serious issues.

If Tenzin is Aang’s son, who is his mother?

DiMartino: [To Konietzko] We can say that, right? [To Speakeasy] It’s Katara. It’s not a huge surprise.

What did you guys think of the live-action version of “The Last Airbender”?

Konietzko: We’re just really focused on this new show right now, and kind of taking this off in its own direction and not concerning ourselves with that right now.

So you didn’t follow the casting controversy about the movie version of “The Last Airbender”?

Konietzko: We didn’t head up that film. We’re just happy to be back generating the original content in this mythology, which is what we do.

Would you like to bring a cartoon version of “Avatar: The Last Airbender” to the big screen?

Konietzko: We would love to. I think Mike and I would absolutely love to do feature animation. Either another story, or it if worked out, one in the “Avatar” world. We would be really excited.