Lock your phone just by contacting DoCoMo.
You can lock your Phonebook and other personal data as well as the "Osaifu-Keitai" IC card function on your phone if you misplace or otherwise loose it. All you have to do is contact DoCoMo by telephone or PC (My DoCoMo). No advance settings are required.
Even if locking fails at the time you apply to activate it, the phone will be locked if communications can be established within 72 hours of application.
简单的说这是个网络锁,相当于PUK码,一般用于防盗(激活后会锁定 IC卡、邮件、附表、电话簿、图像、书签等),就目前的情况看貌似是你机器来源(不是说你的来源,别误会)很有可能是二手或被盗机,DOCOMO官方没有提供自己解决方法,你需要打电话给运营商客服:0120-524-360(日本)
当然了,还需要提供原始签约号码及密码