Japanese Pension Refund

So I returned home from Japan about half a year ago after more than four years working there, and around three months ago applied for my pension refund. I received a letter informing how much I will be entitled to, informing me that I would be receiving the lump sum in several days (this was on January 13th). However, after close to a month, there is still no sign of it.

Is this sort of time period normal or should I be contacting someone?

Yes you will get lumpsump on your the bank which you mention.
If foreigner leave the country forever, they pay lumpsump amount to your bank account. Dont worry about it

The usual deposit period is something like 3-6 months after application (mine was closer to 6 months), however I'm not sure how it relates to when you receive the application acceptance notice. What country are you in? Perhaps there are people from your area with experience?