[mame]

ummm......
When did you send paper letter to his old adress? It takes a certain length of time.

And when did you meet him? Japan Post Office provide a certain service. If my memory is correct, after people moved, Post Office send letters that is sent to old adress to new adress for one year if they offer. And the service can be continued if they offer.

I don't know any homepages where you can search ogawa_san. But I think there are some.