Restraining order?

Does anyone here know what I can do in Japan to an ex boyfriend who just won't leave me alone?he has previous criminal record (DV)and he just doesn't accept that it's over but instead messages me how he's waiting in front of my work place and if I don't get back together with him he'll kill himself etc. Can I get like a restraining order or report him for harrasment or something?im really scared of him..

Please help me...

Have you contacted the police? I think that count as stalking.
But don't expect much, Japanese police are horrible that protecting stalking victims, lol.
I think just recently a high school girl was murdered after reporting the stalker to the police.

No I haven't yet. The last time time he was arrested the police were very helpful...should I show them the emails and such that I have as evidence?or will I just file some kind of a report?should I contact a lawyer?

yes, report to the police again and request protection. show them the emails etc.
Just ask them what reports you need to file if any.