Japanese government sent a large group of Arm force to Iraq but this was been warn to stop sending the army there. Alqedah even announced to attack the people who ever caught, terrorist even admit Tokyo is one of their target. Garbage can in most of the subway and underground has been removed. If you walk and dress suspiciously, you may be questioned by the police on the street.
There are a large number of religions in Japan like Omn, The White's and so on. Most of the religions teaches us not to fight with each other but the meaning has been distorted, they do love each other but among the followers only, for non believer, they consider as alien or outsider. This large group of people have their own way to collect the fund to their God, if you have involved of this, they can never be escaped from it. Must avoid from the beginning.
Japanese Government tried to stop this but has been threaten several times with terror here and there.
Tokyo has one of the lowest crime rates of any large city in the world. I have never felt unsafe, even wandering alone at night in some of the seedier sections. In fact, Tokyo is so safe that it is common to see young Japanese school children riding the trains home alone at night -- there's no reason to worry about their safety. Despite the fact that the Tokyo area has over 23 million people, there are less than 100 murders a year. In fact, a comparison of major crime rates found that Tokyo has about 2500 major crimes per 100,000 people, compared to 7700 in Sydney, 2850 in Seoul, 11,300 in Chicago and 23,000 in Philadelphia. So, when you're in Tokyo, relax!
Japan is considered as one of the most peaceful and safest countries in the world. The community-based security system, the so-called Koban (residential police box) are the backbones of police activities in order to maintain public peace. A Koban is located in urban areas where crimes and accidents are relatively frequent. A Koban is generally manned by one resident officer with his family. The system is drawing worldwide attention as a major factor behind safety in Japan.
In Japan you can stay cool yourself, I mean, most of the people don't commit crime, there are maybe 1 or 2 but mostly they are very conservative about their family dignity and they are just respectful and kind.
There is little crime in Tokyo. It's perfectly safe to walk around the seediest areas imaginable at 4am by yourself (at least for guys) and you need have no fear of being robbed. One of my friends left his wallet in a taxi, and got it back within two days from their lost property office, with all cash and credit cards intact.
Part of the reason for this must be the fact that there are lots and lots of uniformed police on the beat in the city, and almost every intersection has a 'Koban' - signed in Roman script ('English letters' for those of you who don't know what I'm talking about) on a green background - essentially a little office opening onto the street that permanently houses an on-duty police officer. So if you do somehow get in trouble, that's what to look out for. Of course, they probably won't speak much English (or any other language but Japanese), but that's a different story...
If Possible avoid comming here in the Japanese summer holidays (August). I was overwhelmed by the amount of people. At no time did I feel unsafe it was just a little uncomfortable with so many people around.
There are no dangers, really. Tokyo, in fact Japan in general, is extremely safe. You can go walking late at night; if you lose your wallet, you can expect it to be found; if you drop something, someone will pick it up and return it to you. BTW, if you get lost, go to a police box; they're ubiquitous and the cops often help people with directions, even if it's difficult crossing the language barrier.
Tokyo is a safe city. When he first lived there, old Cliffie was amazed to see elementary school kids riding the subway alone. If you lose your wallet on a train, you are likely to get a phone call from the police in the evening to say that it has been found, with the contents intact. Young girls can walk home at night in perfect safety. And everywhere you go, you find high school girls, in short skirts and loose white socks, giggling as they talk on their mobile phones.
There have been no major terrorist incidents in Japan since 1995. Nevertheless, when travelling abroad in any country you should be careful and alert.