Is it possible for a single image to accurately capture a filmmaker's signature themes and aesthetics? For Makoto Shinkai, a decidedly atypical anime director, that image would almost certainly be the railroad crossing. Featured prominently in all his films to date, the crossing has come to represent those rare moments of transition that punctuate adolescence: a brief intersection of passing lives; an impassable distance between potential lovers; and a way-point signaling the juncture of childhood and adult responsibilities. In 5 Centimeters Per Second, Shinkai takes these themes and crafts them into an eloquently told, and beautifully realised tale of bittersweet first love and the disappointments that come along with it.

5 Centimeters Per Second takes its name from the speed at which cherry blossoms - a symbol of transience in Japan - fall from the tree. The cherry blossom here serves as a metaphor for the fragility and brevity of our formative encounters. Composed of three related vignettes, the film revolves around Takaki, a young man on the cusp of adulthood. The first segment recounts Takaki's relationship with Akari, a young girl new to his school. As elementary school ends and the seasons conspire toward the first year of junior high, Akari is forced to move from Tokyo to Tochigi Prefecture. Takaki and Akari communicate via letters, but they gradually become fewer and further between. When Takaki discovers he too will be moving, he arranges to meet Akari, knowing it might be for the last time.

Act 2 finds Takaki enrolled in senior high in Tanegashima. Although he is featured prominently, Takaki isn't the principal protagonist. This time we observe him through the eye of Kanae Sumida, a classmate struggling under the weight of impending school decisions and the most painful kind of first love: she is besotted by Takari but slowly realises that he only has eyes for another girl, Akari. By act 3, Takaki is living alone in Tokyo. He has just separated from his girlfriend when he catches a glimpse of a woman who looks exactly like Akari. Is it her or simply a phantom memory?

Shinkai's depiction of adolescence is certainly sentimental but never cloyingly so. Scenes often border on the hyperreal, imbuing the film with an aching nostalgia which is particularly apparent in Shinkai's use of digital effects. His Japan is one of brilliant dawns and perpetual sunsets. In act 2, the skies over Tanegashima span the range of blues and purples, each one delicately bleeding into the next, lens flares majestically sweep across the screen all set to the symphony of an orchestra of insects. Even Tokyo is rendered with an almost ethereal haze lending a romantic subjectivity to Shinkai's tales.

To better understand Shinkai's films and their reception, it is worth considering the industry climate in which they were released. Many pundits have foreseen a crisis looming. They say fewer young animators are being given the means, or opportunity, to develop as filmmakers, leading to questions of who will replace the industry's most revered directors (Hayao Miyazaki amongst others) as they approach retirement. Satoshi Kon, acclaimed director of Perfect Blue and Paprika, stated: "I know from personal experience [that] the number of animated productions is increasing and that there's not enough staff to go around. There needs to be more education because... those people who have access to technology are often over 40 and they can't work forever."

Shinkai's debut feature, Voices of a Distant Star (2002), was released amidst these fears. The film was something of a revelation, causing many critics to excitedly declare its young director the 'new Miyazaki'. Set in a future Japan (that looks remarkably like the present) Mikako and Noboru are literally star crossed lovers: Mikako is selected as a mecha pilot, cast to the far reaches of our solar system, while, on Earth, Noboru is forced to wait patiently for her return. The couple's only means of contact are their mobile phones, but as the distance that separates them increases so too does the agonising wait between messages.

Voices of a Distant Star created a stir more for its mode of production than its plot (having the unfortunate side effect of overshadowing Shinkai's brilliantly simple and effective premise). The film was created almost single-handedly by Shinkai: he wrote the screenplay, served as director, used all his own designs and animated it using software from his day job at a computer games company. Originally, Shinkai and his girlfriend even voiced Noboru and Mikako, though it was eventually re-recorded by professional actors. Here was a filmmaker who rejected the claims of an industry crisis by producing a film of remarkable power in a manner previously unseen.

Shinkai followed Voices of a Distant Star with a feature length production; The Place Promised in Our Early Days (2004). This time Shinkai worked with a personally selected crew to bolster his vision. The results were mixed. The Place Promised in Our Early Days was certainly visually stunning but even with the extra running time Shinkai failed to unravel the film's cumbersome science-fiction plot. It is tempting to view this shortcoming as the reason Shinkai has side stepped genre trappings for his latest work, but this remains speculation.

At first the Miyazaki comparisons may seem unfounded. With the exception of flight, Shinkai's films share few discernible themes with Miyazaki's and are equally removed visually. In truth, the comparisons don't necessarily refer to the films' content but to the strength and clarity of Shinkai's authorial voice. Like Miyazaki, he infuses every frame with his personal sensibilities. Thematically, Shinkai's work has more in common with the novels of Haruki Murakami and the live action cinema of Hong Kong auteur Wong Kar-Wai. Shinkai's characters may be younger and less idiosyncratic, but they share a deep set melancholy that casts them apart as they struggle to connect with the people around them. After meeting Akari for the last time Takaki begins to feel the sadness of separation before they have even parted, in senior high he writes text messages to himself before deleting them like entries in a distinctly modern journal, finally, as an adult living in Tokyo, his apartment is littered with the debris of loneliness. Here, as in the work of Murakami and Wong Kar-wai, separation is as much about presence as absence; Akari has moved away but her influence permeates everything on screen.

5 Centimeters Per Second is a significant step for Shinkai. His characters are more realised than before and the film's scenarios, though smaller in scale, feel more rounded and complete. With his latest film Shinkai has achieved the emotional resonance that previously lay just beyond his grasp. When he originally planned 5 Centimeters Per Second, the director reportedly envisioned a film of ten chapters. The thought of him developing the remaining seven is certainly an appealing prospect. That said, discovering what lays beyond the railway crossing is even more compelling.