Q: Hello, can you help me ?

The feature you are referring to is called Activation Lock.  You cannot bypass it.  Noone can.  You have to contact the original owner that has their Apple ID attached to that device through Find My iPhone and have them remove the device. 

You can not bypass the activation lock. Chances are high it's a stolen phone. That aside, even if you did manage to get past that, you can't use it in your country. Japanese phones are carrier locked and the Japanese carriers do not offer unlocking.

Return it and get your money back.

If you don't have that information, you cannot use the phone. That is the activation security in iOS 7.

No, no one here can help you.

No. No one can help you. As you've already been told, the phone is probably stolen. There is no way to bypass the activation lock, and even if you could, you can not use it on a carrier other than the one it's locked to.