Child custody advice

I (US Citizen / Japan PR) am separated from my wife (Japanese). We have been separated for almost three years. We are still married on paper as there was no reason to officially divorce and I did not know/trust anything about child custody laws in Japan. I wanted to keep my daughter (now 13) as my daughter.

Everything was fine and I was able to visit my daughter and her visit me until a few months ago when my daughter stopped replying to my emails and answering my phone calls.

This is not unusual for short periods of time if she is busy with other things like school or club, but she always at least replies to tell me she got my message and then gets back to me shortly.

The only means I have to contact her is via her "Kid's Phone" which is a special cell phone that only accepts calls and emails from myself, her mother, and her grandmother.

She does not have any other internet access as her mother keeps it tightly restricted.

I have sent letters via normal post including self-addressed stamped postcards so all she needs to do it drop it into a mailbox to let me know that she is OK and that she received it, but still no response.

Her mother now does not reply to emails or phone either. (Generally I only send emails because I want to have written record of all communication, but in this case I tried to phone her as well)

I have avoided, until now, trying to assert any type of legal custody directives (if there are any) because it seemed that everything was going OK and her mother was responsive whenever I contacted her about our daughter and I felt there was no need to make things messy or "force" my daughter to spend specific days at specific houses as she has her own friends and activity schedule as well and I know that her mother will frame me as the bad guy and if a visit interferes with daughter's plan mother will say "You HAVE TO because Daddy is making you."

I have tried to keep everything civil and reasonable taking daughter's feelings and wishes into account as well. Now, however, I can not get ahold of her to make plans, nor her mother.

I feel that it is time that I have to get law involved. Without any response from her mother, however, I do not know how to proceed.

The thought crossed my mind to call the police and report it as an abduction or missing person, but I think that is too much, but without being able to contact them I do not know the next step.

Any suggestions?

what contribution have you made for the child raising ?
have you been paying some (and sufficient) money for that purpose ?

The above response is irrelevant to you questions.

If you have done all you can to access visitation, then it is time to lawyer up.