Virtuosity: "Summer Wars"

2008's The Girl Who Leapt Through Time suggested director Mamoru Hosoda might have mastered one form of Japanese animation: the kind that while soaringly high of concept and possessed of action enough to appeal to the traditional fanbase of teenagers, also preserves a breezy, lyrical, emotionally satisfying core that could equally be savoured by grown-ups. Hosoda's 2009 follow-up Summer Wars, reissued in UK cinemas this weekend, considers just one of the ways in which society might break down in coming decades, but it does so from a distance, unfolding around a country retreat reminiscent of Mizoguchi or Kurosawa movies; it touches grass, in other words, and gives itself space to think. Young hero Kenji jumps at the chance of a summer job that would bring him closer to his beloved Natsuki, only to discover it's a non-paying position: pretending to be her boyfriend at the birthday party her family are throwing for their 90-year-old matriarch. While prepared to play along, Kenji opens up a can of worms between appointments when he accidentally breaches the security of Oz, a vast online social network; the consequent cybercollapse has knock-on effects in the real world, first taking out satnavs and e-mail accounts, and eventually threatening to bring about full-scale nuclear holocaust. Oopsie.

As an end-of-the-world speculation, it has as much of a sense of multiple events going on at once - a developing space-probe crisis, a high-school baseball championship - as any Jerry Bruckheimer blockbuster, yet Hosoda keeps turning his camera on lovely, evocative details: a soft drink can rattling on the ledge of a train window, a ferocious uncle's selection of faded motor-industry vests. In doing so, he anchors, keeps simple and makes surprisingly affecting a plot taking place in two realities at once. Oz is a busy, rainbow-coloured utopia, home to a staggering array of effects and possibilities - until it's taken over by a dark angel whose vast fist, made up of countless stolen avatars, snatches up the identities of online users. (AI fascism much?) But Hosoda delights in the real world, too: its history (much is made of the fact Natsuki's family are the descendants of samurai), its analogue diversions (a card game called Koi Koi becomes important during the finale), its messy human interactions (all the problems are caused by a black-sheep figure seeking the attention his nearest and dearest have thus far denied to him). A little more sedentary than its predecessor, it nevertheless confirms Hosoda as an animator with a rare feeling for character: the nervy hero, whose blushes seem to upload to his face, is very much in the lineage of The Girl Who Leapt Through Time, making a mistake he then has to correct, but the movie's moral centre is Natsuki's grandmother, who hasn't been near a computer in her life, and knows how to get things done by, you know, actually talking to people in person.

Summer Wars opens in selected cinemas from Sunday.