Interior Design is about a young couple, Hiroko and Akira, who have come to Tokyo to show Akira's film, carting the reels and the smoke-effects machine in the back of their car.
"We are not kids anymore."
Tokyo as they enter is a drenched city (forbidding music over sky-scrapers seen from rainswept windows and with Akira providing a narration of a future), landscape filled with mutants, is alienating and at the same time cozy. The crampedness of the car and then the apartment of their friend Akemi is somehow very comfortable. And the city allows them the possibility of getting busy with the activity of Growing Up. But it's Hiroko that wants to grow up because in some ways Akira, the immature creative mind, is already an adult, confident in his abilities, able to navigate the city and gets a job without even trying. He is easily able to translate the strangeness of the city into imaginary terms, loves his weird, silly but kind of awesome looking film and is mostly very comfortable in his skin.
The same can't be said of Hiroko. And this is actually her story, the story of her trying to find the right ambition for herself.

Michel Gondy is a strange genius, with a unique aesthetic sense that is ever-evolving, from the music-videos that he did early on to Mood Indigo last year. There is something infectious in his style; he is the imaginative 10-yr old we always wished we were. And here he is working with Japanese culture, so Kawaii-centered images, amazingly little typography and colour patterns jumps out of the frame. His sensibility permeates all of this film, from the hand-crafted pastel shaded sets (but which are probably very carefully selected and immense hard-work went into making it look so accidentally cute) to the clothes the characters wear (even the school uniforms that Hiroko and Akira wear in a photo seen for a fraction of a second is so absolutely spot-on) to a general sense of half-asleep whimsy of the things that happen in the story, just on the right-side of surreal.
And all to tell the story of a young woman who hasn't developed completely as a person.

As Hiroko searches for an apartment in the city, feels hostility from her best-friend for being a free-loader, and figures out a way to get Akira's film reels from her impounded car, (a film which she probably doesn't like) she begins to question what she is doing here. The pop-corn lady at the theater where the film is being screened understands her: it's is very hard being attached to a creative person. You have to subsume your own desires to theirs. And her problem is that she isn't that confident of herself, hasn't found herself or what she is good at.
So in a surreal beautiful sequence she becomes a chair, starts living in another artist's home, invisible but useful, necessary but disposable.