•If the deadline passes without the certificate - 1 month after leaving mid-year, otherwise January 31 of the following year - you can file a notification of non-issuance of a withholding certificate with the tax office for your place of tax payment. Attach copies of any pay statements you have, plus anything showing you asked your employer for it
•Filing a tax return may result in a refund of overpaid taxes
•Reissuing a certificate you have already received is outside the scope of the non-issuance notification procedure, so keep it safe once you have it
•If you become freelance or self-employed, filing a tax return (kakutei shinkoku) becomes mandatory
•The NTA states explicitly that 'all recipients' includes foreign employees who are residents - those with an address in Japan or a place of residence there for a year or more - and that the certificate must be issued to them