While Japan's video-game industry no longer dominates the world, there is still one niche of digital entertainment that this country does better than any other: romantic man-machine interaction.

Love with a virtual being is something plucked straight out of science-fiction. But in Tokyo's Akihabara district, hundreds of dating-simulation games are sold in stores, aimed directly at an audience of otaku (obsessive hobbyists). The most successful of these is the "LovePlus" series, in which players strike up a relationship with an on-screen character and pursue her through daily interactions.

The games are on Nintendo's portable DS and 3DS consoles, allowing players to take their "girlfriend" anywhere, and it unfolds in more or less real-time — meaning that if you make a date with your girlfriend at 7 p.m. next Friday, you'd better boot up the game at 7 p.m. next Friday, or risk being chastised for standing her up. Much of the courtship takes place within a high school, with the protagonist and other characters as students, and flirting opportunities seized between lessons or in the library may result in dates somewhere further afield — which I'll come back to later. The actual relationship is played out through dialogue trees that allow the characters to chat about love and other affairs of the heart and mind.