Freaky Friday‘s body swap story posed some interesting questions. How would it feel to wake up, look in the mirror and see the face of Lindsay Lohan? How would it feel to be trapped inside someone else’s skin? But one question it failed to ask was: what if the person you swapped bodies with was of the opposite sex? What if you woke up, peered down under the covers and saw a penis instead of a vagina? That would take the idea to a whole new level of WTF. Right?

That’s exactly where Japanese anime Your Name – the number-one movie in Japan for nine weeks running – dares to go. The story sees two teens – a boy from Tokyo, a girl from the sticks – inexplicably swap bodies overnight. The boy, trapped in his new female body, peers down at his breasts in disbelief. He has a feel. The girl, too, is curious. They swap bodies a bunch of times and have fun toying with each other’s lives, organising dates, leaving text messages. But why is this happening to them? Does it have something to do with the enormous comet passing over Japan, perhaps?

As Makoto Shinkai’s high-concept anime unspools, a will-they-won’t-they romance emerges against a backdrop of a looming eco-disaster. It’s a teen body-swap comedy that’s part love story, part disaster movie. And it’s hard to think of anything quite like it. When i-D sat down with Shinkai, we asked him why he thinks the film has struck a chord in Japan, how the country’s deadly 2011 earthquake shaped its story, and how it feels to be hailed as ‘the heir to Hayao Miyazaki’.

Where did you get the idea for this boy-girl swap story?
The boy-girl swap theme is quite common in Japanese fictional stories – films, mangas – and actually about a thousand years ago there was a story about this man-woman body swap [Torikaebaya Monogatari]. But the aspect is only a part of the film, it begins as that but it doesn’t end like that. So I wanted to surprise people, because people think, ‘oh it’s about a boy-girl body swap’, when the film isn’t just about that.

It was like seeing a teen movie done as an animation. Do you think it’s harder to capture the nuances of coming-of-age in animation versus live-action?
I don’t think one is more difficult than the other; they’re just two different things. But with live-action movies it’s the director’s creation but half the film is influenced by the actors, whereas animation everything is mine. We create characters for the film, so the characters don’t play other characters. So if you want to tell stories genuinely, I think animation is one of the best formats… There are things that are common with live-action movies – shots of hands and feet and everything else – but I don’t find it particularly more difficult because I’m drawing the characters. I’m in control.

The film has been hugely successful in Japan. What do you think it is about it that’s drawn so many people in?
To be honest, I want to know myself. But I think I was really lucky. There are many animation films made in Japan and they’re really good, but I think this one is a very straightforward boy-meets-girl story, and there must have been a sort of hidden demand among young people for that. They really were looking for a good boy-meets-girl story and I think my film came out at just the right time.

Fans have even visited the real-life locations that the film was modelled on. How important was that for you, working from real-life locations?
I simply wanted to show: this is where I live and it’s beautiful. I want everybody to see it. Tokyo is beautiful and yet you can find lots of negative stuff – packed trains, really busy places. So it’s nice to find hidden gems and I think that will cheer people up and I want people in Tokyo to feel that Tokyo is beautiful, that would make me feel proud. I get people from abroad coming to Japan saying, “I love your film and that’s why we came here.” So that’s great.

There’s the idea of a natural disaster looming – was that threat of destruction something you took from real life in Japan?
Yes, and without that big earthquake in 2011, this story would have been completely different. That incident really reminded us how vulnerable Japan is. There’s a line in the film – “you never know when Tokyo will go” – and I think people are conscious about that. It’s not like people are thinking about it everyday, but I think people are aware of how vulnerable our land is, so I wanted to create some sort of miracle; it’s not just about sadness.

How do you think real-life teens in Japan would react if they knew destruction was coming?
It’s hard to tell but realistically speaking, there’s not much that teenagers can do. In this movie, the comet comes and what the teenagers would do is go to the mayors and get the adults involved, because they can’t really do much. So the important thing about this is that it’s a fictional story, but I didn’t want it to be unrealistic, so I didn’t want teenagers to create some sort of miracle; I really wanted them to go to the adults and try to think of what to do, which is more realistic I think.

Did you have any cinematic influences?
Interstellar by Christopher Nolan. I saw it while I was making this film, and I found quite a few similarities. And there’s another movie, from Korea, called The Beauty Inside, which is about a character who wakes up in the morning as a different person every day. So I thought it confirms that what I’m making now is now, it’s current. I felt encouraged by other directors because I’m going in the right direction.

You’ve been called the heir to Miyazaki. How do you respond to that?
I feel really honoured, but that’s too much! Miyazaki is way, way above. Yes, I broke the box-office record, but this is just once; Miyazaki has done it so many times and yes, I want to make more of an effort to get closer to where he is now.

Your Name arrive to select UK cinemas 18th November and nationwide 24th November.