Oliver Arlow: Behind bright lights can lurk the darkest secrets
The mistake that many people make when they first arrive in Tokyo is that they are completely safe. The neon of Shibuya is beguiling, the shops of the Ginza tempting and restaurants, bars and clubs throughout the city are accessible and welcoming.
This is true even of foreign visitors who do not know the language, culture or customs.
Although only visitors to Tokyo, Nicola Furlong and her friend would have had the same experience walking around the city as any western women.
They may have attracted a few glances, but they are more likely to have been jealous ones from Japanese women coveting their hair than aggressive ones from men with other things on their mind.
Japanese are an unfailingly polite -- particularly towards foreigners and foreign women, terrified of causing offence by saying or doing the wrong thing.
But then, as we know, it was not Japanese men who posed a threat on the night Ms Furlong was killed and her friend assaulted.
Cynics say the Metropolitan Police Department is happy to have most foreigners corralled into one part of the city as it is easier to keep an eye on what they are up to.
In recent years, the embassies of Britain, the US and Australia have issued warnings to people to be on their guard against an upsurge in women having their drinks spiked with date-rape drugs such as Rohypnol.
On top of that, people in bars are known to have credit cards scanned and thousands of dollars charged to their accounts.
In 2004, four expatriate businessmen died and at least 12 others were taken seriously ill after snorting cocaine that local dealers had secretly mixed with heroin.
Murders, overdoses and assaults are aberrations on everyday life in Japan, for foreigners as well as local people. But they happen.
On the face of it though, foreign visitors could be excused for seeing no threat in this neon metropolis.
Even amid the back alleys of the sprawling Kabuki-cho red light district, close to Shinjuku Station, there is none of the sense of menace or just-under-the-surface tensions that are part of the seediest quarters of other big cities around the world.
The country rightly has a reputation as being among the most crime-free countries in the world, particularly when it comes to violent crime.
Which is perhaps why people let their guard down when they land in Tokyo and fail to take the precautions they would as a matter of course in Detroit, Delhi or Dublin.
Tokyo is so large and convoluted that it often seems like several cities that have been pushed together.
At its heart is the moated Imperial Palace, which appears as a large dark spot amid constantly moving lights as soon as the sun has gone down.
Many neighbouring areas are home to businesses that are household names around the world -- the names Sony, Panasonic and Sharp atop skyscrapers and picked out against the skyline.
This familiarity can make a visitor feel at home.
Beyond the business districts are a series of self-contained mini-cities that have grown up largely where the constantly circulating loop of the Yamanote railway line intersects with the tracks that take commuters to their homes in the suburbs.
But often, instead of changing immediately from one commuter train to another, a salary-man or office lady will stop off with friends for a quick drink at a bar or 'izakaya', the local equivalent of a sit-down pub with a counter, small plates of food and lots of alcohol.
These are the hubs of Shibuya and Shinjuku, Ueno, Ikebukuro, Ebisu and Shinagawa. Each has a thriving 'gaijin' -- or foreigner -- following and a blonde woman is certainly not out of place.
But while a generally placid society, there are, of course, exceptions. In 2000, Joji Obara drugged British-born Lucie Blackman and raped her at his beach-side apartment south of Tokyo.
On a day out to the beach, Obara spiked 21-year-old Lucie's drink, causing a fatal reaction that killed her.
He cut up her body with a chainsaw and buried it in a cave on the beach. After his arrest, it was reported that Obara had drugged and raped hundreds of other women.
Seven years later, Lindsay Hawker was assaulted in the apartment of a man that she had been teaching English.
Lindsay (22) was raped and her body buried in sand in a bath tub on the balcony of the apartment east of Tokyo. Her killer, Tatsuya Ichihashi, lived as a casual labourer for almost three years before being finally apprehended.